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Start Over Author "Kurtanidze, S" Topic astrophysics - high energy astrophysical phenomena
44 results on '"Kurtanidze, S"'

1. Optical variability of the blazar 3C 371: from minute to year timescales

Author

Otero-Santos, J., Raiteri, C. M., Acosta-Pulido, J. A., Carnerero, M. I., Villata, M., Savchenko, S. S., Carosati, D., Chen, W. P., Kurtanidze, S. O., Joner, M. D., Semkov, E., Pursimo, T., Benítez, E., Damljanovic, G., Apolonio, G., Borman, G. A., Bozhilov, V., Galindo-Guil, F. J., Grishina, T. S., Hagen-Thorn, V. A., Hiriart, D., Hsiao, H. Y., Ibryamov, S., Ivanidze, R. Z., Kimeridze, G. N., Kopatskaya, E. N., Kurtanidze, O. M., Larionov, V. M., Larionova, E. G., Larionova, L. V., Minev, M., Morozova, D. A., Nikolashvili, M. G., Ovcharov, E., Sigua, L. A., Stojanovic, M., Troitskiy, I. S., Troitskaya, Yu. V., Tsai, A., Valcheva, A., Vasilyev, A. A., Vince, O., Zaharieva, E., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The BL Lac object 3C 371 has been observed by the Transiting Exoplanet Survey Satellite (\textit{TESS}) for approximately a year, between July 2019 and July 2020, with an unmatched 2-minute observing cadence. In parallel, the Whole Earth Blazar Telescope (WEBT) Collaboration organized an extensive observing campaign, providing three years of continuous optical monitoring between 2018 and 2020. These datasets allow for a thorough investigation of the variability of the source. The goal of this study is evaluating the optical variability of 3C 371. Taking advantage of the remarkable cadence of \textit{TESS} data, we aim to characterize the intra-day variability (IDV) displayed by the source and identify its shortest variability timescale. With this estimate, constraints on the size of the emitting region and black hole mass can be calculated. Moreover, WEBT data is used to investigate long-term variability (LTV), including understanding spectral behaviour of the source and the polarization variability. Based on the derived characteristics, information on the origin of the variability on different timescales is extracted. We evaluated the variability applying the variability amplitude tool that quantifies how variable the emission is. Moreover, we employed common tools like ANOVA (ANalysis Of VAariance) tests, wavelet and power spectral density (PSD) analyses to characterize the shortest variability timescales present in the emission and the underlying noise affecting the data. Short- and long-term colour behaviours have been evaluated to understand the spectral behaviour of the source. The polarized emission was analyzed, studying its variability and possible rotation patterns of the electric vector position angle (EVPA). Flux distributions of IDV and LTV were also studied with the aim of linking the flux variations to turbulent and/or accretion disc related processes., Comment: Accepted in A&A, 20 pages, 19 figures

Published
2024
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2. The variability patterns of the TeV blazar PG 1553+113 from a decade of MAGIC and multi-band observations

Author

MAGIC Collaboration, Abe, H., Abe, S., Abhir, J., Acciari, V. A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Batković, I., Baxter, J., González, J. Becerra, Bernardini, E., Bernete, J., Berti, A., Besenrieder, J., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Burelli, I., Busetto, G., Campoy-Ordaz, A., Carosi, A., Carosi, R., Carretero-Castrillo, M., Castro-Tirado, A. J., Chai, Y., Cifuentes, A., Cikota, S., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., Fariña, L., Fattorini, A., Foffano, L., Font, L., Fukami, S., Fukazawa, Y., López, R. J. García, Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Grau, R., Green, J. G., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hovatta, T., Hrupec, D., Hütten, M., Imazawa, R., Inada, T., Iotov, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kerszberg, D., Kluge, G. W., Kobayashi, Y., Kouch, P. M., Kubo, H., Kushida, J., Lezáun, M. Láinez, Lamastra, A., Leone, F., Lindfors, E., Liodakis, I., Lombardi, S., Longo, F., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mannheim, K., Mariotti, M., Martínez, M., Martínez-Chicharro, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., González, M. Molero, Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Nakamori, T., Nanci, C., Neustroev, V., Nigro, C., Nikolić, L., Nilsson, K., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavlović, D., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Sahakyan, N., Saito, T., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sciaccaluga, A., Sitarek, J., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Suda, Y., Suutarinen, S., Tajima, H., Takeishi, R., Tavecchio, F., Temnikov, P., Terauchi, K., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Ventura, S., Verguilov, V., Viale, I., Vigorito, C. F., Vitale, V., Walter, R., Wunderlich, C., Yamamoto, T., collaborators, MWL, Jermak, H., Steele, I. A., Smith, P. S., Blinov, D., Raiteri, C. M., Villata, M., Mirzaqulov, D. O., Kurtanidze, S. O., Carosati, D., Savchenko, S. S., Acosta-Pulido, J. A., Borman, G. A., Bozhilov, V., Carnerero, M. I., Chigladze, R. A., Damljanovic, G., Ehgamberdiev, S. A., Feige, M., Grishina, T. S., Gupta, A. C., Hagen-Thorn, V. A., Ibryamov, S., Ivanidze, R. Z., Jorstad, S. G., Kania, J., Kimeridze, G. N., Kopatskaya, E. N., Kopp, M., Kunkel, L., Kurtanidze, O. M., Larionov, V. M., Larionova, E. G., Larionova, L. V., Lorey, C., Marchini, A., Marscher, A. P., Minev, M., Morozova, D. A., Nikolashvili, M. G., Ovcharov, E., Reinhart, D., Sadun, A. C., Scherbantin, A., Schneider, L., Semkov, E., Sigua, L. A., Steineke, R., Troitskaya, Yu. V., Troitskiy, I. S., Valcheva, A., Vasilyev, A. A., Vince, O., Zaharieva, E., Zottmann, N., Kiehlmann, S., Readhead, A., Max-Moerbeck, W., Reeves, R. A., Sandrinelli, A., Ramazani, V. Fallah, Giroletti, M., Righini, S., Marchili, N., Patricelli, B., Ghirlanda, G., and Lico, R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

PG 1553+113 is one of the few blazars with a convincing quasi-periodic emission in the gamma-ray band. The source is also a very high-energy (VHE; >100 GeV) gamma-ray emitter. To better understand its properties and identify the underlying physical processes driving its variability, the MAGIC Collaboration initiated a multiyear, multiwavelength monitoring campaign in 2015 involving the OVRO 40-m and Medicina radio telescopes, REM, KVA, and the MAGIC telescopes, Swift and Fermi satellites, and the WEBT network. The analysis presented in this paper uses data until 2017 and focuses on the characterization of the variability. The gamma-ray data show a (hint of a) periodic signal compatible with literature, but the X-ray and VHE gamma-ray data do not show statistical evidence for a periodic signal. In other bands, the data are compatible with the gamma-ray period, but with a relatively high p-value. The complex connection between the low and high-energy emission and the non-monochromatic modulation and changes in flux suggests that a simple one-zone model is unable to explain all the variability. Instead, a model including a periodic component along with multiple emission zones is required., Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society. 19 pages, 9 figures. Corresponding authors: Elisa Prandini, Antonio Stamerra, Talvikki Hovatta

Published
2024
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3. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and $\gamma$-ray brightness levels

Author

Raiteri, C. M., Villata, M., Carnerero, M. I., Savchenko, S. S., Kurtanidze, S. O., Vlasyuk, V. V., Marchini, A., Matsumoto, K., Lorey, C., Joner, M. D., Gazeas, K., Carosati, D., Mirzaqulov, D. O., Pulido, J. A. Acosta, Agudo, I., Bachev, R., Benítez, E., Borman, G. A., Calcidese, P., Chen, W. P., Damljanovic, G., Ehgamberdiev, S. A., Elsässer, D., Feige, M., Frasca, A., Gaur, H., Grishina, T. S., Gupta, A. C., Hiriart, D., Holland, M., Horst, B., Ibryamov, S., Ivanidze, R. Z., Jensen, J., Jithesh, V., Jovanovic, M. D., Kiehlmann, S., Kimeridze, G. N., Kishore, S., Kopatskaya, E. N., Kurtanidze, O. M., Larionova, E. G., Lin, H. C., Mannheim, K., Marinelli, C., Reyes, J. Moreira, Morozova, D. A., Nikolashvili, M. G., Reinhart, D., Romanov, F. D., Semkov, E., Seufert, J., Shishkina, E. V., Sigua, L. A., Skalidis, R., Spiridonova, O. I., Stojanovic, M., Strigachev, A., Troitskaya, Y. V., Troitskiy, I. S., Tsai, A., Vasilyev, A. A., Vince, O., Vrontaki, K., Wani, K., Watts, D., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and $\gamma$-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to $\gamma$-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and $\gamma$-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates., Comment: 12 pages, 13 figures, in press for MNRAS

Published
2023

4. Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES~2344+514

Author

Abe, H., Abe, S., Acciari, V. A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Batković, I., Baxter, J., González, J. Becerra, Bernardini, E., Bernete, J., Berti, A., Besenrieder, J., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bošjak, Ž, Burelli, I., Busetto, G., Campoy-Ordaz, A., Carosi, A., Carosi, R., Carretero-Castrillo, M., Castro-Tirado, A. J., Chai, Y., Cifuentes, A., Cikota, S., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Ammando, F., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., Fariña, L., Fattorini, A., Foffano, L., Font, L., Fukami, S., Fukazawa, Y., López, R. J. García, Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Grau, R., Green, J. G., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hrupec, D., Hütten, M., Imazawa, R., Inada, T., Iotov, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kerszberg, D., Kluge, G. W., Kobayashi, Y., Kouch, P. M., Kubo, H., Kushida, J., Lezáun, M. Láinez, Lamastra, A., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mariotti, M., Martínez, M., Martínez-Chicharro, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., González, M. Molero, Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Nakamori, T., Nanci, C., Neustroev, V., Nigro, C., Nikolić, L., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavlović, D., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Sahakyan, N., Saito, T., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sciaccaluga, A., Sitarek, J., Spolon, A., Stamerra, A., Strišović, J., Strom, D., Suda, Y., Tajima, H., Takeishi, R., Tavecchio, F., Temnikov, P., Terauchi, K., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Ventura, S., Verguilov, V., Viale, I., Vigorito, C. F., Vitale, V., Walter, R., Wunderlich, C., Leto, T. Yamamoto M. Perri F. Verrecchia C., Das, S., Chatterjee, R., Raiteri, C. M., Villata, M., Semkov, E., Ibryamov, S., Bachev, R., Strigachev, A., Damljanovic, G., Vince, O., Jovanovic, M. D., Stojanovic, M., Larionov, V. M., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Morozova, D. A., Savchenko, S. S., Troitskiy, I. S., Troitskaya, Y. V., Vasilyev, A. A., Chen, W. P., Hou, W. J., Lin, C. S., Tsai, A., Jorstad, S. G., Weaver, Z. R., Acosta-Pulido, J. A., Carnerero, M. I., Carosati, D., Kurtanidze, S. O., Kurtanidze, O. M., Jordan, B., Ivanidze, R. Z., Gazeas, K., Vrontaki, K., Hovatta, T., Liodakis, I., Readhead, A. C. S., Kiehlmann, S., Zheng, W., and Filippenko, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron SED peak energy $\nu_{synch,p}$ above 1keV). While those extreme states were so far observed only during high flux levels, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to VHE performed so far, focusing on a systematic characterisation of the intermittent extreme states. While our results confirm that 1ES 2344+514 typically exhibits $\nu_{synch,p}>$1keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase of the electron acceleration efficiency without a change in the electron injection luminosity. We also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of $\nu_{synch,p}$. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common harder-when-brighter trend observed in BL Lacs is violated. During a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This UV excess implies that at least two regions contribute significantly to the infrared/optical/ultraviolet/X-ray emission. Using the simultaneous MAGIC, XMM-Newton, NuSTAR, and AstroSat observations, we argue that a region possibly associated with the 10 GHz radio core may explain such an excess. Finally, we investigate a VHE flare, showing an absence of simultaneous variability in the 0.3-2keV band. Using a time-dependent leptonic modelling, we show that this behaviour, in contradiction to single-zone scenarios, can instead be explained by a two-component model., Comment: Accepted for publication in Astronomy & Astrophysics

Published
2023
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5. The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics

Author

Raiteri, C. M., Villata, M., Jorstad, S. G., Marscher, A. P., Pulido, J. A. Acosta, Carosati, D., Chen, W. P., Joner, M. D., Kurtanidze, S. O., Lorey, C., Marchini, A., Matsumoto, K., Mirzaqulov, D. O., Savchenko, S. S., Strigachev, A., and Vince, O.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical data in the BVRI bands acquired at 36 observatories around the world. In mid 2021 the source showed its historical maximum, with R = 11.14. The light curves display many episodes of intraday variability, whose amplitude increases with source brightness, in agreement with a geometrical interpretation of the long-term flux behaviour. This is also supported by the long-term spectral variability, with an almost achromatic trend with brightness. In contrast, short-term variations are found to be strongly chromatic and are ascribed to energetic processes in the jet. We also analyse the optical polarimetric behaviour, finding evidence of a strong correlation between the intrinsic fast variations in flux density and those in polarisation degree, with a time delay of about 13 h. This suggests a common physical origin. The overall behaviour of the source can be interpreted as the result of two mechanisms: variability on time scales greater than several days is likely produced by orientation effects, while either shock waves propagating in the jet, or magnetic reconnection, possibly induced by kink instabilities in the jet, can explain variability on shorter time scales. The latter scenario could also account for the appearance of quasi-periodic oscillations, with periods from a few days to a few hours, during outbursts, when the jet is more closely aligned with our line of sight and the time scales are shortened by relativistic effects., Comment: 15 pages, 16 figures, submitted to MNRAS

Published
2023
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6. Multi-messenger characterization of Mrk 501 during historically low X-ray and $\gamma$-ray activity

Author

MAGIC collaboration, Abe, H., Abe, S., Acciari, V. A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., Baxter, J., González, J. Becerra, Bednarek, W., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Burelli, I., Busetto, G., Carosi, R., Carretero-Castrillo, M., Castro-Tirado, A. J., Ceribella, G., Chai, Y., Chilingarian, A., Cikota, S., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Espiñeira, E. Do Souto, Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., Ramazani, V. Fallah, Fariña, L., Fattorini, A., Foffano, L., Font, L., Fruck, C., Fukami, S., Fukazawa, Y., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Grau, R., Green, D., Green, J. G., Hadasch, D., Hahn, A., Hassan, T., Heckmann, L., Herrera, J., Hrupec, D., Hütten, M., Imazawa, R., Inada, T., Iotov, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Lyard, E., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mangano, S., Mannheim, K., Mariotti, M., Martínez, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Moreno, V., Nakamori, T., Nanci, C., Nava, L., Neustroev, V., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sitarek, J., Sliusar, V., Sobczynska, D., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Tajima, H., Takahashi, M., Takeishi, R., Tavecchio, F., Temnikov, P., Terauchi, K., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Viale, I., Vigorito, C. F., Vitale, V., Vovk, I., Walter, R., Will, M., Wunderlich, C., Yamamoto, T., Zarić, D., groups, Other, collaborations, Cerruti, M., Acosta-Pulido, J. A., Apolonio, G., Bachev, R., Baloković, M., Benítez, E., Björklund, I., Bozhilov, V., Brown, L. F., Bugg, A., Carbonell, W., Carnerero, M. I., Carosati, D., Casadio, C., Chamani, W., Chen, W. P., Chigladze, R. A., Damljanovic, G., Epps, K., Erkenov, A., Feige, M., Finke, J., Fuentes, A., Gazeas, K., Giroletti, M., Grishina, T. S., Gupta, A. C., Gurwell, M. A., Heidemann, E., Hiriart, D., Hou, W. J., Hovatta, T., Ibryamov, S., Joner, M. D., Jorstad, S. G., Kania, J., Kiehlmann, S., Kimeridze, G. N., Kopatskaya, E. N., Kopp, M., Korte, M., Kotas, B., Koyama, S., Kramer, J. A., Kunkel, L., Kurtanidze, S. O., Kurtanidze, O. M., Lähteenmäki, A., López, J. M., Larionov, V. M., Larionova, E. G., Larionova, L. V., Leto, C., Lorey, C., Mújica, R., Madejski, G. M., Marchili, N., Marscher, A. P., Minev, M., Modaressi, A., Morozova, D. A., Mufakharov, T., Myserlis, I., Nikiforova, A. A., Nikolashvili, M. G., Ovcharov, E., Perri, M., Raiteri, C. M., Readhead, A. C. S., Reimer, A., Reinhart, D., Righini, S., Rosenlehner, K., Sadun, A. C., Savchenko, S. S., Scherbantin, A., Schneider, L., Schoch, K., Seifert, D., Semkov, E., Sigua, L. A., Singh, C., Sola, P., Sotnikova, Y., Spencer, M., Steineke, R., Stojanovic, M., Strigachev, A., Tornikoski, M., Traianou, E., Tramacere, A., Troitskaya, Yu. V., Troitskiy, I. S., Trump, J. B., Tsai, A., Valcheva, A., Vasilyev, A. A., Verrecchia, F., Villata, M., Vince, O., Vrontaki, K., Weaver, Z. R., Zaharieva, E., and Zottmann, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We study the broadband emission of Mrk 501 using multi-wavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi-LAT, NuSTAR, Swift, GASP-WEBT, and OVRO. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wavebands, with the highest occurring at X-rays and very-high-energy (VHE) $\gamma$-rays. A significant correlation ($>$3$\sigma$) between X-rays and VHE $\gamma$-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between Swift-XRT and Fermi-LAT. We additionally find correlations between high-energy $\gamma$-rays and radio, with the radio lagging by more than 100 days, placing the $\gamma$-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE $\gamma$-rays from mid-2017 to mid-2019 with a stable VHE flux ($>$0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2-year-long low-state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED towards the low-state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock., Comment: 55 pages, 30 figures, 14 tables, accepted by APJS. Corresponding authors are L. Heckmann, D. Paneque, S. Gasparyan, M. Cerruti, and N. Sahakyan

Published
2022
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7. Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

Author

MAGIC Collaboration, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Artero, M., Asano, K., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Blanch, O., Bošnjak, Ž., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Espiñeira, E. Do Souto, Prester, D. Dominis, Donini, A., Doro, M., Ramazani, V. Fallah, Fattorini, A., Ferrara, G., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Green, J. G., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jiménez, I., Jormanainen, J., Jouvin, L., Kajiwara, Y., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., Peñil, P., Perennes, C., Persic, M., Moroni, P. G. Prada, Prandini, E., Priyadarshi, C., Puljak, I., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schmidt, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Zarić, D., Collaboration, FACT, Baack, D., Balbo, M., Biederbeck, N., Biland, A., Bretz, T., Buss, J., Dorner, D., Eisenberger, L., Elsaesser, D., Hildebrand, D., Iotov, R., Mannheim, K., Neise, D., Noethe, M., Paravac, A., Rhode, W., Schleicher, B., Sliusar, V., Walter, R., groups, Other, collaborations, D'Ammando, F., Horan, D., Lien, A. Y., Baloković, M., Madejski, G. M., Perri, M., Verrecchia, F., Leto, C., Lähteenmäki, A., Tornikoski, M., Ramakrishnan, V., Järvelä, E., Vera, R. J. C., Villata, M., Raiteri, C. M., Gupta, A. C., Pandey, A., Fuentes, A., Agudo, I., Casadio, C., Semkov, E., Ibryamov, S., Marchini, A., Bachev, R., Strigachev, A., Ovcharov, E., Bozhilov, V., Valcheva, A., Zaharieva, E., Damljanovic, G., Vince, O., Larionov, V. M., Borman, G. A., Grishina, T. S., Hagen-Thorn, V. A., Kopatskaya, E. N., Larionova, E. G., Larionova, L. V., Morozova, D. A., Nikiforova, A. A., Savchenko, S. S., Troitskiy, I. S., Troitskaya, Y. V., Vasilyev, A. A., Merkulova, O. A., Chen, W. P., Samal, M., Lin, H. C., Moody, J. W., Sadun, A. C., Jorstad, S. G., Marscher, A. P., Weaver, Z. R., Feige, M., Kania, J., Kopp, M., Kunkel, L., Reinhart, D., Scherbantin, A., Schneider, L., Lorey, C., Acosta-Pulido, J. A., Carnerero, M. I., Carosati, D., Kurtanidze, S. O., Kurtanidze, O. M., Nikolashvili, M. G., Chanishvili, R. G., Chigladze, R. A., Ivanidze, R. Z., Kimeridze, G. N., Sigua, L. A., Joner, M. D., Spencer, M., Giroletti, M., Marchili, N., Righini, S., Rizzi, N., and Bonnoli, G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an extensive multiwavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina and Mets\"ahovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance during a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. Our multi-band correlation study also hints at an anti-correlation between UV/optical and X-ray at a significance higher than 3 sigmas. A VHE flare observed on 2017 February 4 shows gamma-ray variability on multi-hour timescales, with a factor 10 increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors., Comment: 38 pages, 23 figures, accepted for publication in Astronomy and Astrophysics. Corresponding authors: Axel Arbet-Engels, David Paneque

Published
2021
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8. The dual nature of blazar fast variability. Space and ground observations of S5 0716+714

Author

Raiteri, C. M., Villata, M., Carosati, D., Benítez, E., Kurtanidze, S. O., Gupta, A. C., Mirzaqulov, D. O., D'Ammando, F., Larionov, V. M., Pursimo, T., Acosta-Pulido, J. A., Baida, G. V., Balmaverde, B., Bonnoli, G., Borman, G. A., Carnerero, M. I., Chen, W. -P., Dhiman, V., Di Maggio, A., Ehgamberdiev, S. A., Hiriart, D., Kimeridze, G. N., Kurtanidze, O. M., Lin, C. S., Lopez, J. M., Marchini, A., Matsumoto, K., Mujica, R., Nakamura, M., Nikiforova, A. A., Nikolashvili, M. G., Okhmat, D. N., Otero-Santos, J., Rizzi, N., Sakamoto, T., Semkov, E., Sigua, L. A., Stiaccini, L., Troitsky, I. S., Tsai, A. L., Vasilyev, A. A., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Blazar S5 0716+714 is well-known for its short-term variability, down to intra-day time-scales. We here present the 2-min cadence optical light curve obtained by the TESS space telescope in 2019 December - 2020 January and analyse the object fast variability with unprecedented sampling. Supporting observations by the Whole Earth Blazar Telescope Collaboration in B, V , R, and I bands allow us to investigate the spectral variability during the TESS pointing. The spectral analysis is further extended in frequency to the UV and X-ray bands with data from the Neil Gehrels Swift Observatory. We develop a new method to unveil the shortest optical variability time-scales. This is based on progressive de-trending of the TESS light curve by means of cubic spline interpolations through the binned fluxes, with decreasing time bins. The de-trended light curves are then analysed with classical tools for time-series analysis (periodogram, auto-correlation and structure functions). The results show that below 3 d there are significant characteristic variability time-scales of about 1.7, 0.5, and 0.2 d. Variability on time-scales < 0.2 d is strongly chromatic and must be ascribed to intrinsic energetic processes involving emitting regions, likely jet sub-structures, with dimension less than about milliparsec. In contrast, flux changes on time-scales > 0.5 d are quasi-achromatic and are probably due to Doppler factor changes of geometric origin., Comment: 17 pages, 18 figures, accepted by MNRAS

Published
2020
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9. Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution

Author

Weaver, Zachary R., Williamson, K. E., Jorstad, S. G., Marscher, A. P., Larionov, V. M., Raiteri, C. M., Villata, M., Acosta-Pulido, J. A., Bachev, R., Baida, G. V., Balonek, T. J., Benitez, E., Borman, G. A., Bozhilov, V., Carnerero, M. I., Carosati, D., Chen, W. P., Damljanovic, G., Dhiman, V., Dougherty, D. J., Ehgamberdiev, S. A., Grishina, T. S., Gupta, A. C., Hart, M., Hiriart, D., Hsiao, H. Y., Ibryamov, S., Joner, M., Kimeridze, G. N., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Matsumoto, K., Matsumura, R., Minev, M., Mirzaqulov, D. O., Morozova, D. A., Nikiforova, A. A., Nikolashvili, M. G., Ovcharov, E., Rizzi, N., Sadun, A., Savchenko, S. S., Semkov, E., Slater, J. J., Smith, K. L., Stojanovic, M., Strigachev, A., Troitskaya, Yu. V., Troitsky, I. S., Tsai, A. L., Vince, O., Valcheva, A., Vasilyev, A. A., Zaharieva, E., and Zhovtan, A. V.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena
Abstract

In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations of BL Lacertae over a wide wavelength range: with the \emph{Transiting Exoplanet Survey Satellite} (TESS) at 6,000-10,000 \AA\ with 2-minute cadence; with the Neil Gehrels \emph{Swift} satellite at optical, UV, and X-ray bands; with the Nuclear Spectroscopic Telescope Array at hard X-ray bands; with the \emph{Fermi} Large Area Telescope at $\gamma$-ray energies; and with the Whole Earth Blazar Telescope for measurement of the optical flux density and polarization. All light curves are correlated, with similar structure on timescales from hours to days. The shortest timescale of variability at optical frequencies observed with TESS is $\sim 0.5$ hr. The most common timescale is $13\pm1$~hr, comparable with the minimum timescale of X-ray variability, 14.5 hr. The multi-wavelength variability properties cannot be explained by a change solely in the Doppler factor of the emitting plasma. The polarization behavior implies that there are both ordered and turbulent components to the magnetic field in the jet. Correlation analysis indicates that the X-ray variations lag behind the $\gamma$-ray and optical light curves by up to $\sim 0.4$ days. The timescales of variability, cross-frequency lags, and polarization properties can be explained by turbulent plasma that is energized by a shock in the jet and subsequently loses energy to synchrotron and inverse Compton radiation in a magnetic field of strength $\sim3$ G, Comment: 33 pages, 25 figures, 14 tables. Accepted to ApJ

Published
2020

10. The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Baack, D., Babić, A., Banerjee, B., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Espiñera, E. Do Souto, Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Fernández-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Godinović, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nöthe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Surić, T., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tsujimoto, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Will, M., Zarić, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, Svetlana G., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, Alan P., Max-Moerbeck, W., Moody, J. Ward, Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, Alberto C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., and Villata, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of February, 2010 when an extraordinary flare reaching a level of $\sim$27~Crab Units above 1~TeV was measured in very-high-energy (VHE) $\gamma$-rays with the VERITAS observatory. This is the highest flux state for Mrk 421 ever observed in VHE $\gamma$-rays. Data are analyzed from a coordinated campaign across multiple instruments including VHE $\gamma$-ray (VERITAS, MAGIC), high-energy (HE) $\gamma$-ray (Fermi-LAT), X-ray (Swift}, RXTE, MAXI), optical (including the GASP-WEBT collaboration and polarization data) and radio (Mets\"ahovi, OVRO, UMRAO). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare `decline' epochs. The main flare statistics allow 2-minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of $\sim$25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor ($\delta \gtrsim 33$) and the size of the emission region ($ \delta^{-1}R_B \lesssim 3.8\times 10^{13}\,\,\mbox{cm}$) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10-minute-binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship: from linear to quadratic to lack of correlation to anti-correlation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain by the classic single-zone synchrotron self-Compton model., Comment: 41 pages including 3 appendices, 13 figures; version accepted to Astrophysical Journal

Published
2020
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11. Unravelling the complex behavior of Mrk 421 with simultaneous X-ray and VHE observations during an extreme flaring activity in April 2013

Author

MAGIC collaboration, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Baack, D., Babic, A., Banerjee, B., de Almeida, U. Barres, Barrio, J. A., Gonzalez, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bosnjak, Z., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Puppo, F., Delfino, M., Delgado, J., Depaoli, D., Di Pierro, F., Di Venere, L., Espineira, E. Do Souto, Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Ferrara, G., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Lopez, R. J. Garcia, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinovic, N., Green, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Hutten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jouvin, L., Kajiwara, Y., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Loporchio, S., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Mender, S., Micanovic, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletic, L., Penil, P., Peresano, M., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Suric, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Tosti, L., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Zaric, D., groups, Other, Petropoulou, M., Finke, J., D'Ammando, F., Balokovic, M., Madejski, G., Mori, K., Puccetti, Simonetta, Leto, C., Perri, M., Verrecchia, F., Villata, M., Raiteri, C. M., Agudo, I., Bachev, R., Berdyugin, A., Blinov, D. A., Chanishvili, R., Chen, W. P., Chigladze, R., Damljanovic, G., Eswaraiah, C., Grishina, T. S., Ibryamov, S., Jordan, B., Jorstad, S. G., Joshi, M., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Larionov, V. M., Latev, G., Lin, H. C., Marscher, A. P., Mokrushina, A. A., Morozova, D. A., Nikolashvili, M. G., Semkov, E., Smith, P. S., Strigachev, A., Troitskaya, Yu. V., Troitsky, I. S., Vince, O., Barnes, J., Guever, T., Moody, J. W., Sadun, A. C., Hovatta, T., Richards, J. L., Max-Moerbeck, W., Readhead, A. C. R., Lahteenmaki, A., Tornikoski, M., Tammi, J., Ramakrishnan, V., and Reinthal, R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on a multi-band variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 2013 April 19. The study uses, among others, data from GASP-WEBT, Swift, NuSTAR, Fermi-LAT, VERITAS, and MAGIC. The large blazar activity, and the 43 hours of simultaneous NuSTAR and MAGIC/VERITAS observations, permitted variability studies on 15 minute time bins, and over three X-ray bands (3-7 keV, 7-30 keV and 30-80 keV) and three very-high-energy (>0.1 TeV, hereafter VHE) gamma-ray bands (0.2-0.4 TeV, 0.4-0.8 TeV and >0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy-independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-ray and the VHE gamma rays. The three VHE bands and the three X-ray bands are positively correlated with no time-lag, but the strength and the characteristics of the correlation changes substantially over time and across energy bands. Our findings favour multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux-flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer., Comment: 46 pages, 17 figures, 9 tables, accepted for publication in ApJ Supplements

Published
2020
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12. Multiwavelength behaviour of the blazar 3C279: decade-long study from $\gamma$-ray to radio

Author

Larionov, V. M., Jorstad, S. G., Marscher, A. P., Villata, M., Raiteri, C. M., Smith, P. S., Agudo, I., Savchenko, S. S., Morozova, D. A., Acosta-Pulido, J. A., Aller, M. F., Aller, H. D., Andreeva, T. S., Arkharov, A. A., Bachev, R., Bonnoli, G., Borman, G. A., Bozhilov, V., Calcidese, P., Carnerero, M. I., Carosati, D., Casadio, C., Chen, W. -P., Damljanovic, G., Dementyev, A. V., Di Paola, A., Frasca, A., Fuentes, A., Gómez, J. L., Gónzalez-Morales, P., Giunta, A., Grishina, T. S., Gurwell, M. A., Hagen-Thorn, V. A., Hovatta, T., Ibryamov, S., Joshi, M., Kiehlmann, S., Kim, J. -Y., Kimeridze, G. N., Kopatskaya, E. N., Kovalev, Yu. A., Kovalev, Y. Y., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Lázaro, C., Larionova, L. V., Larionova, E. G., Leto, G., Marchini, A., Matsumoto, K., Mihov, B., Minev, M., Mingaliev, M. G., Mirzaqulov, D., Dimitrova, R. V. Muñoz, Myserlis, I., Nikiforova, A. A., Nikolashvili, M. G., Nizhelsky, N. A., Ovcharov, E., Pressburger, L. D., Rakhimov, I. A., Righini, S., Rizzi, N., Sadakane, K., Sadun, A. C., Samal, M. R., Sanchez, R. Z., Semkov, E., Sergeev, S. G., Sigua, L. A., Slavcheva-Mihova, L., Sola, P., Sotnikova, Yu. V., Strigachev, A., Thum, C., Traianou, E., Troitskaya, Yu. V., Troitsky, I. S., Tsybulev, P. G., Vasilyev, A. A., Vince, O., Weaver, Z. R., Williamson, K. E., and Zhekanis, G. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

We report the results of decade-long (2008-2018) $\gamma$-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, $\it{Fermi}$ and $\it{Swift}$ data, as well as polarimetric and spectroscopic data. The X-ray and $\gamma$-ray light curves correlate well, with no delay > 3 hours, implying general co-spatiality of the emission regions. The $\gamma$-ray-optical flux-flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz VLBA images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain $\gamma$-ray variability on very short time scales. The Mg II emission line flux in the `blue' and `red' wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands we find progressive delays of the most prominent light curve maxima with decreasing frequency, as expected from the frequency dependence of the $\tau=1$ surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at $\sim5$ GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet., Comment: 21 pages, 18 figures, accepted for publication in MNRAS

Published
2020
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13. Investigating the multiwavelength behaviour of the flat spectrum radio quasar CTA 102 during 2013-2017

Author

D'Ammando, F., Raiteri, C. M., Villata, M., Acosta-Pulido, J. A., Agudo, I., Arkharov, A. A., Bachev, R., Baida, G. V., Benitez, E., Borman, G. A., Boschin, W., Bozhilov, V., Butuzova, M. S., Calcidese, P., Carnerero, M. I., Carosati, D., Casadio, C., Castro-Segura, N., Chen, W. -P., Damljanovic, G., Di Paola, A., Echevarria, J., Efimova, N. V., Ehgamberdiev, Sh. A., Espinosa, C., Fuentes, A., Giunta, A., Gomez, J. L., Grishina, T. S., Gurwell, M. A., Hiriart, D., Jermak, H., Jordan, B., Jorstad, S. G., Joshi, M., Kimeridze, G. N., Kopatskaya, E. N., Kuratov, K., Kurtanidze, O. M., Kurtanidze, S. O., Lahteenmaki, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Lazaro, C., Lin, C. S., Malmrose, M. P., Marscher, A. P., Matsumoto, K., McBreen, B., Michel, R., Mihov, B., Minev, M., Mirzaqulov, D. O., Molina, S. N., Moody, J. W., Morozova, D. A., Nazarov, S. V., Nikiforova, A. A., Nikolashvili, M. G., Ohlert, J. M., Okhmat, N., Ovcharov, E., Pinna, F., Polakis, T. A., Protasio, C., Pursimo, T., Redondo-Lorenzo, F. J., Rizzi, N., Rodriguez-Coira, G., Sadakane, K., Sadun, A. C., Samal, M. R., Savchenko, S. S., Semkov, E., Sigua, L., Skiff, B. A., Slavcheva-Mihova, L., Smith, P. S., Steele, I. A., Strigachev, A., Tammi, J., Thum, C., Tornikoski, M., Troitskaya, Yu. V., Troitsky, I. S., Vasilyev, A. A., Vince, O., Hovatta, T., Kiehlmann, S., Max-Moerbeck, W., Readhead, A. C. S., Reeves, R., Pearson, T. J., Mufakharov, T., Sotnikova, Yu. V., and Mingaliev, M. G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi ($\gamma$ rays) satellites to study flux and spectral variability and the correlation between flux changes at different wavelengths. Unprecedented $\gamma$-ray flaring activity was observed during 2016 November-2017 February, with four major outbursts. A peak flux of (2158 $\pm$ 63)$\times$10$^{-8}$ ph cm$^{-2}$ s$^{-1}$, corresponding to a luminosity of (2.2 $\pm$ 0.1)$\times$10$^{50}$ erg s$^{-1}$, was reached on 2016 December 28. These four $\gamma$-ray outbursts have corresponding events in the near-infrared, optical, and UV bands, with the peaks observed at the same time. A general agreement between X-ray and $\gamma$-ray activity is found. The $\gamma$-ray flux variations show a general, strong correlation with the optical ones with no time lag between the two bands and a comparable variability amplitude. This $\gamma$-ray/optical relationship is in agreement with the geometrical model that has successfully explained the low-energy flux and spectral behaviour, suggesting that the long-term flux variations are mainly due to changes in the Doppler factor produced by variations of the viewing angle of the emitting regions. The difference in behaviour between radio and higher energy emission would be ascribed to different viewing angles of the jet regions producing their emission., Comment: 24 pages, 18 figures, and 4 tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society

Published
2019
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14. Optical Variability of TeV Blazars on long time-scales

Author

Gaur, Haritma, Gupta, Alok C., Bachev, R., Strigachev, A., Semkov, E., Wiita, P. J., Kurtanidze, O. M., Darriba, A., Damljanovic, G., Chanishvili, R. G., Ibryamov, S., Kurtanidze, S. O., Nikolashvili, M. G., Sigua, L. A., and Vince, O.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results of photometric observations of three TeV blazars, 3C 66A, S5 0954+658 and BL Lacertae, during the period 2013--2017. Our extensive observations were performed in a total of 360 nights which produced $\sim$6820 image frames in BVRI bands. We study flux and spectral variability of these blazars on these lengthy timescales. We also examine the optical Spectral Energy Distributions of these blazars, which are crucial in understanding the emission mechanism of long-term variability in blazars. All three TeV blazars exhibited strong flux variability during our observations. The colour variations are mildly chromatic on long timescales for two of them. The nature of the long-term variability of 3C 66A and S5 0954+658 is consistent with a model of a non-thermal variable component that has a continuous injection of relativistic electrons with power law distributions around 4.3 and 4.6, respectively. However, the long-term flux and colour variability of BL Lac suggests that these can arise from modest changes in velocities or viewing angle toward the emission region, leading to variations in the Doppler boosting of the radiation by a factor ~1.2 over the period of these observations., Comment: 13 pages, 15 figures, Accepted for publication in MNRAS

Published
2019
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15. The extreme HBL behaviour of Markarian 501 during 2012

Author

Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Babić, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Berti, A., Bhattacharyya, W., Blanch, O., Bonnoli, G., Carosi, R., Carosi, A., Chatterjee, A., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Cumani, P., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Doert, M., Domínguez, A., Prester, D. Dominis, Doro, M., Glawion, D. Eisenacher, Engelkemeier, M., Ramazani, V. Fallah, Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Gaug, M., Giammaria, P., Godinović, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Kuveždić, D., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Minev, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peresano, M., Perri, L., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Garcia, J. R., Reichardt, I., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Satalecka, K., Schroeder, S., Schweizer, T., Shore, S. N., Sitarek, J., Šnidarić, I., Sobczynska, D., Stamerra, A., Strzys, M., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Treves, A., Tsujimoto, S., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Ward, J. E., Will, M., Zarić, D., Arbet-Engels, A., Baack, D., Balbo, M., Biland, A., Blank, M., Bretz, T., Bruegge, K., Bulinski, M., Buss, J., Dmytriiev, A., Dorner, D., Einecke, S., Elsaesser, D., Herbst, T., Hildebrand, D., Kortmann, L., Linhoff, L., Mahlke, M., Mannheim, K., Mueller, S. A., Neise, D., Neronov, A., Noethe, M., Oberkirch, J., Paravac, A., Rhode, W., Schleicher, B., Schulz, F., Sedlaczek, K., Shukla, A., Sliusar, V., Walter, R., Archer, A., Benbow, W., Bird, R., Brose, R., Buckley, J. H., Bugaev, V., Christiansen, J. L., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Gillanders, G. H., Gueta, O., Hanna, D., Hervet, O., Holder, J., Hughes, G., Hütten, M., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhel, A., Williams, D. A., Williamson, T. J, Zitzer, B., Perri, M., Verrecchia, F., Leto, C., Villata, M., Raiteri, C. M., Jorstad, S. G., Larionov, V. M., Blinov, D. A., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Nikiforova, A. A., Morozova, D. A., Troitskaya, Yu. V., Troitsky, I. S., Kurtanidze, O. M., Nikolashvili, M. G., Kurtanidze, S. O., Kimeridze, G. N., Chigladze, R. A., Strigachev, A., Sadun, A. C., Moody, J. W., Chen, W. P., Lin, H. C., Acosta-Pulido, J. A., Arévalo, M. J., Carnerero, M. I., González-Morales, P. A., Manilla-Robles, A., Jermak, H., Steele, I., Mundel, C., Benítez, E., Hiriart, D., Smith, P. S., Max-Moerbeck, W., Readhead, A. C. S., Richards, J. L., Hovatta, T., Lähteenmäki, A., Tornikoski, M., Tammi, J., Georganopoulos, M., and Baring, M. G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of $\sim$0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was $\sim$3 CU, and the peak of the high-energy spectral component was found to be at $\sim$2 TeV. This study reports very hard X-ray spectra, and the hardest VHE spectra measured to date for Mrk 501. The fractional variability was found to increase with energy, with the highest variability occurring at VHE, and a significant correlation between the X-ray and VHE bands. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency- peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The one-zone synchrotron self-Compton (SSC) scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behaviour seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays., Comment: 25 pages, 9 figures, accepted for publication in A&A. Corresponding authors: Gareth Hughes (gareth.hughes@cfa.harvard.edu), David Paneque (dpaneque@mppmu.mpg.de), Amit Shukla (amit.shukla@astro.uni-wuerzburg.de)

Published
2018
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16. The ever-surprising blazar OJ 287: multi-wavelength study and appearance of a new component in X-rays

Author

Kushwaha, Pankaj, Gupta, Alok C., Wiita, Paul J., Pal, Main, Gaur, Haritma, Pino, E. M. de Gouveia Dal, Kurtanidze, O. M., Semkov, E., Damljanovic, G., Hu, S. M., Uemura, M., Vince, O., Darriba, A., Gu, M. F., Bachev, R., Chen, Xu, Itoh, R., Kawabata, M., Kurtanidze, S. O., Nakaoka, T., Nikolashvili, M. G., Sigua, L. A., Strigachev, A., and Zhang, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

We present a multi-wavelength spectral and temporal investigation of OJ 287 emission during its strong optical-to-X-ray activity between July 2016 - July 2017. The daily $\gamma$-ray fluxes from \emph{Fermi}-LAT are consistent with no variability. The strong optical-to-X-ray variability is accompanied by a change in power-law spectral index of the X-ray spectrum from $< 2$ to $>2$, with variations often associated with changes in optical polarization properties. Cross-correlations between optical-to-X-ray emission during four continuous segments show simultaneous optical-ultraviolet (UV) variations while the X-ray and UV/optical are simultaneous only during the middle two segments. In the first segment, the results suggest X-rays lag the optical/UV, while in the last segment X-rays lead by $\sim$ 5-6 days. The last segment also shows a systematic trend with variations appearing first at higher energies followed by lower energy ones. The LAT spectrum before the VHE activity is similar to preceding quiescent state spectrum while it hardens during VHE activity period and is consistent with the extrapolated VHE spectrum during the latter. Overall, the broadband spectral energy distributions (SEDs) during high activity periods are a combination of a typical OJ 287 SED and an HBL SED, and can be explained in a two-zone leptonic model, with the second zone located at parsec scales, beyond the broad line region, being responsible for the HBL-like spectrum. The change of polarization properties from systematic to chaotic and back to systematic, before, during and after the VHE activity, suggest dynamic roles for magnetic fields and turbulence., Comment: 13 pages, 4 figures, 2 tables, MNRAS accepted version

Published
2018
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17. The Bright $\gamma$-ray Flare of 3C 279 in June 2015: AGILE Detection and Multifrequency Follow-up Observations

Author

Pittori, C., Lucarelli, F., Verrecchia, F., Raiteri, C. M., Villata, M., Vittorini, V., Tavani, M., Puccetti, S., Perri, M., Donnarumma, I., Vercellone, S., Acosta-Pulido, J. A., Bachev, R., Benitez, E., Borman, G. A., Carnerero, M. I., Carosati, D., Chen, W. P., Ehgamberdiev, Sh. A., Goded, A., Grishina, T. S., Hiriart, D., Hsiao, H. Y., Jorstad, S. G., Kimeridze, G. N., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionov, V. M., Larionova, L. V., Marscher, A. P., Mirzaqulov, D. O., Morozova, D. A., Nilsson, K., Samal, M. R., Sigua, L. A., Spassov, B., Strigachev, A., Takalo, L. O., Antonelli, L. A., Bulgarelli, A., Cattaneo, P., Colafrancesco, S., Giommi, P., Longo, F., Morselli, A., and Paoletti, F.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the AGILE detection and the results of the multifrequency follow-up observations of a bright $\gamma$-ray flare of the blazar 3C 279 in June 2015. We use AGILE-GRID and Fermi-LAT $\gamma$-ray data, together with Swift-XRT, Swift-UVOT, and ground-based GASP-WEBT optical observations, including polarization information, to study the source variability and the overall spectral energy distribution during the $\gamma$-ray flare. The $\gamma$-ray flaring data, compared with as yet unpublished simultaneous optical data which allow to set constraints on the big blue bump disk luminosity, show very high Compton dominance values of $\sim 100$, with a ratio of $\gamma$-ray to optical emission rising by a factor of three in a few hours. The multi-wavelength behavior of the source during the flare challenges one-zone leptonic theoretical models. The new observations during the June 2015 flare are also compared with already published data and non-simultaneous historical 3C 279 archival data., Comment: 13 pages, 5 figures,5 Tables. Accepted for publication in ApJ

Published
2018
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18. Characterizing optical variability of OJ 287 in 2016 - 2017

Author

Gupta, Alok C., Gaur, Haritma, Wiita, Paul J., Pandey, A., Kushwaha, P., Hu, S. M., Kurtanidze, O. M., Semkov, E., Damljanovic, G., Goyal, A., Uemura, M., Darriba, A., Chen, Xu, Vince, O., Gu, M. F., Zhang, Z., Bachev, R., Chanishvili, R., Itoh, R., Kawabata, M., Kurtanidze, S. O., Nakaoka, T., Nikolashvili, M. G., Stawarz, L., and Strigachev, A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on a recent multi-band optical photometric and polarimetric observational campaign of the blazar OJ 287 which was carried out during September 2016 -- December 2017. We employed nine telescopes in Bulgaria, China, Georgia, Japan, Serbia, Spain and the United States. We collected over 1800 photometric image frames in BVRI bands and over 100 polarimetric measurements over ~175 nights. In 11 nights with many quasi-simultaneous multi-band (V, R, I) observations, we did not detect any genuine intraday variability in flux or color. On longer timescales, multiple flaring events were seen. Large changes in color with respect to time and in a color--magnitude diagram were seen, and while only a weak systematic variability trend was noticed in color with respect to time, the color--magnitude diagram shows a bluer-when-brighter trend. Large changes in the degree of polarization, and substantial swings in the polarization angle were detected. The fractional Stokes parameters of the polarization showed a systematic trend with time in the beginning of these observations, followed by chaotic changes and then an apparently systematic variation at the end. These polarization changes coincide with the detection and duration of the source at very high energies as seen by VERITAS. The spectral index shows a systematic variation with time and V-band magnitude. We briefly discuss possible physical mechanisms that could explain the observed flux, color, polarization, and spectral variability., Comment: 16 pages, 8 figures, 7 tables; Accepted for Publication to AJ

Published
2018
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19. Multi-wavelength temporal and spectral variability of the blazar OJ 287 during and after the December 2015 flare: a major accretion disc contribution

Author

Kushwaha, P., Gupta, A. C., Wiita, P. J., Gaur, H., Pino, E. M. de Gouveia Dal, Bhagwan, J., Kurtanidze, O. M., Larionov, V. M., Damljanovic, G., Uemura, M., Semkov, E., Strigachev, A., Bachev, R., Vince, O., Gu, Minfeng, Zhang, Z., Abe, T., Agarwal, A., Borman, G. A., Fan, J. H., Grishina, T. S., Hirochi, J., Itoh, R., Kawabata, M., Kopatskaya, E. N., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Mishra, A., Morozova, D. A., Nakaoka, T., Nikolashvili, M. G., Savchenko, S. S., Troitskaya, Yu. V., Troitsky, I. S., and Vasilyev, A. A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

We present a multi-wavelength spectral and temporal analysis of the blazar OJ 287 during its recent activity between December 2015 -- May 2016, showing strong variability in the near-infrared (NIR) to X-ray energies with detection at $\gamma$-ray energies as well. Most of the optical flux variations exhibit strong changes in polarization angle and degree. All the inter-band time lags are consistent with simultaneous emissions. Interestingly, on days with excellent data coverage in the NIR--UV bands, the spectral energy distributions (SEDs) show signatures of bumps in the visible--UV bands, never seen before in this source. The optical bump can be explained as accretion-disk emission associated with the primary black hole of mass $\sim \rm 1.8 \times10^{10} M_{\odot}$ while the little bump feature in the optical-UV appears consistent with line emission. Further, the broadband SEDs extracted during the first flare and during a quiescent period during this span show very different $\gamma$-ray spectra compared to previously observed flare or quiescent spectra. The probable thermal bump in the visible seems to have been clearly present since May 2013, as found by examining all available NIR-optical observations, and favors the binary super-massive black hole model. The simultaneous multi-wavelength variability and relatively weak $\gamma$-ray emission that shows a shift in the SED peak is consistent with $\gamma$-ray emission originating from inverse Compton scattering of photons from the line emission that apparently contributes to the little blue bump., Comment: 24 pages, 6 figures, 2 tables, MNRAS in press

Published
2017
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20. The Variability and Period Analysis for the BL Lac AO 0235+164

Author

Fan, J. H., Kurtanidze, O., Liu, Y., Liu, X., Yang, J. H., Richter, G. M., Nikolashvili, M. G., Kurtanidze, S. O., Wang, H. T., Sasada, M., Zhou, A. Y., Lin, C., Yuan, Y. H., Zhang, Y. T., and Constantin, D.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Variability is one of the extreme observational properties of BL Lacertae objects. AO 0235+164 is a well studied BL Lac through the whole electro-magnetic wavebands. In the present work, we show its optical R band photometric observations carried out during the period of Nov, 2006 to Dec. 2012 using the Ap6E CCD camera attached to the primary focus of the $\rm 70-cm$ meniscus telescope at Abastumani Observatory, Georgia. It shows a large variation of $\Delta R$ = 4.88 mag (14.19 - 19.07 mag) and a short time scale of $\Delta T_v$ = 73.5 min during our monitoring period. During the period of Dec. 2006 to Nov. 2009, we made radio observations of the source using the 25-m radio telescope at Xinjiang Astronomical Observatory. When a discrete correlation function (DCF) is adopted to the optical and radio observations, we found that the optical variation leads the radio variation by 23.2$\pm$12.9 days., Comment: Accepted by ApJ

Published
2017
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21. Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009

Author

Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Berti, A., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Buson, S., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Wilhelmi, E. de Ona, Di Pierro, F., Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Glawion, D. Eisenacher, Elsaesser, D., Engelkemeier, M., Ramazani, V. Fallah, Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Godinović, N., Munoz, A. González, Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nilsson, K., Nishijima, K., Noda, K., Nogués, L., Overkemping, A., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Pedaletti, G., Peresano, M., Perri, L., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Saito, T., Satalecka, K., Schröder, S., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Vanzo, G., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Abeysekara, A. U., Archambault, S., Archer, A., Benbow, W., Bird, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Dickinson, H. J., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Flinders, A., Fortson, L., Gillanders, G. H., Griffin, S., Grube, J., Hütten, M., Hanna, D., Holder, J., Humensky, T. B., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Maier, G., McCann, A., Moriarty, P., Mukherjee, R., Nieto, D., O'Brien, S., Ong, R. A., Otte, N., Park, N., Perkins, J., Pichel, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Telezhinsky, I., Tucci, J. V., Tyler, J., Wakely, S. P., Weinstein, A., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Razzaque, S., Villata, M., Raiteri, C. M., Aller, H. D., Aller, M. F., Larionov, V. M., Arkharov, A. A., Blinov, D. A., Efimova, N. V., Grishina, T. S., Hagen-Thorn, V. A., Kopatskaya, E. N., Larionova, L. V., Larionova, E. G., Morozova, D. A., Troitsky, I. S., Ligustri, R., Calcidese, P., Berdyugin, A., Kurtanidze, O. M., Nikolashvili, M. G., Kimeridze, G. N., Sigua, L. A., Kurtanidze, S. O., Chigladze, R. A., Chen, W. P., Koptelova, E., Sakamoto, T., Sadun, A. C., Moody, J. W., Pace, C., Pearson III, R., Yatsu, Y., Mori, Y., Carraminyana, A., Carrasco, L., de la Fuente, E., Norris, J. P., Smith, P. S., Wehrle, A., Gurwell, M. A., Zook, Alma, Pagani, C., Perri, M., Capalbi, M., Cesarini, A., Krimm, H. A., Kovalev, Y. Y., Kovalev, Yu. A., Ros, E., Pushkarev, A. B., Lister, M. L., Sokolovsky, K. V., Kadler, M., Piner, G., Lähteenmäki, A., Tornikoski, M., Angelakis, E., Krichbaum, T. P., Nestoras, I., Fuhrmann, L, Zensus, J. A., Cassaro, P., Orlati, A., Maccaferri, G., Leto, P., Giroletti, M., Richards, J. L., Max-Moerbeck, W., and Readhead, A. C. S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1 which includes, among other instruments, MAGIC, VERITAS, Whipple 10-m, Fermi-LAT, RXTE, Swift, GASP-WEBT and VLBA. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found in the acquired data set. The higher variability in the very high energy (>100 GeV, VHE) gamma-ray emission and the lack of correlation with the X-ray emission indicate that the highest-energy electrons that are responsible for the VHE gamma-rays do not make a dominant contribution to the ~1 keV emission. Alternatively, there could be a very variable component contributing to the VHE gamma-ray emission in addition to that coming from the synchrotron self-Compton (SSC) scenarios. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters. We find that there is some degeneracy in both the one-zone and the two-zone SSC scenarios that were probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The SSC model grid-scan shows that the flaring activity around 2009 May 22 cannot be modeled adequately with a one-zone SSC scenario, while it can be suitably described within a two-independent-zone SSC scenario. The observation of an electric vector polarization angle rotation coincident with the gamma-ray flare from 2009 May 1 resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties., Comment: 33 pages, 15 figures, accepted for publication in A&A. Corresponding authors: Marlene Doert (marlene.doert@tu-dortmund.de) and David Paneque (dpaneque@mppmu.mpg.de)

Published
2016
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22. Multiband optical variability of the blazar OJ 287 during its outbursts in 2015 -- 2016

Author

Gupta, Alok C., Agarwal, A., Mishra, A., Gaur, H., Wiita, P. J., Gu, M. F., Kurtanidze, O. M., Damljanovic, G., Uemura, M., Semkov, E., Strigachev, A., Bachev, R., Vince, O., Zhang, Z., Villarroel, B., Kushwaha, P., Pandey, A., Abe, T., Chanishvili, R., Chigladze, R. A., Fan, J. H., Hirochi, J., Itoh, R., Kanda, Y., Kawabata, M., Kimeridze, G. N., Kurtanidze, S. O., Latev, G., Dimitrova, R. V. Muñoz, Nakaoka, T., Nikolashvili, M. G., Shiki, K., Sigua, L. A., and Spassov, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present recent optical photometric observations of the blazar OJ 287 taken during September 2015 -- May 2016. Our intense observations of the blazar started in November 2015 and continued until May 2016 and included detection of the large optical outburst in December 2016 that was predicted using the binary black hole model for OJ 287. For our observing campaign, we used a total of 9 ground based optical telescopes of which one is in Japan, one is in India, three are in Bulgaria, one is in Serbia, one is in Georgia, and two are in the USA. These observations were carried out in 102 nights with a total of ~ 1000 image frames in BVRI bands, though the majority were in the R band. We detected a second comparably strong flare in March 2016. In addition, we investigated multi-band flux variations, colour variations, and spectral changes in the blazar on diverse timescales as they are useful in understanding the emission mechanisms. We briefly discuss the possible physical mechanisms most likely responsible for the observed flux, colour and spectral variability., Comment: 11 pages, 6 figures, 4 tables; Accepted for publication in MNRAS

Published
2016
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23. Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

Author

MAGIC Collaboration, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Buson, S., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Wilhelmi, E. de Oña, Di Pierro, F., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Glawion, D. Eisenacher, Elsaesser, D., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Godinović, N., Muñoz, A. González, Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nilsson, K., Nishijima, K., Noda, K., Nogués, L., Orito, R., Overkemping, A., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Pedaletti, G., Perri, L., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Saito, T., Satalecka, K., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Blinov, D. A., Chen, W. P., Efimova, N. V., Forné, E., Grishina, T. S., Hovatta, T., Jordan, B., Kimeridze, G. N., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmaäki, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Ligustri, R., Lin, H. C., McBreen, B., Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Ros, J. A., Sadun, A. C., Sigua, L. A., Tornikoski, M., Troitsky, I. S., and Villata, M.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year time scales, which can bring additional insight on the processes responsible for its broadband emission. We observed Mrk 421 in the very high energy (VHE) gamma-ray range with the Cherenkov telescope MAGIC-I from March 2007 to June 2009 for a total of 96 hours of effective time after quality cuts. The VHE flux variability is quantified with several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes for the first time. The 2.3 year long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Mets\"ahovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year time scales. Mrk 421 was found in different gamma-ray emission states during the 2.3 year long observation period. Flares and different levels of variability in the gamma-ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Mets\"ahovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. The fractional variability is overall increasing with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and gamma-ray photons are either the same, as expected in the Synchrotron-Self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades., Comment: Corresponding authors: Ann-Kristin Overkemping (ann-kristin.overkemping@tu-dortmund.de), Marina Manganaro (manganaro@iac.es), Diego Tescaro (diego.tescaro@gmail.com), To be published in Astronomy&Astrophysics (A&A), 12 pages, 9 figures

Published
2016
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24. Polarization angle swings in blazars: The case of 3C 279

Author

Kiehlmann, S., Savolainen, T., Jorstad, S. G., Sokolovsky, K. V., Schinzel, F. K., Marscher, A. P., Larionov, V. M., Agudo, I., Akitaya, H., Benítez, E., Berdyugin, A., Blinov, D. A., Bochkarev, N. G., Borman, G. A., Burenkov, A. N., Casadio, C., Doroshenko, V. T., Efimova, N. V., Fukazawa, Y., Gómez, J. L., Grishina, T. S., Hagen-Thorn, V. A., Heidt, J., Hiriart, D., Itoh, R., Joshi, M., Kawabata, K. S., Kimeridze, G. N., Kopatskaya, E. N., Korobtsev, I. V., Krajci, T., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Lindfors, E., López, J. M., McHardy, I. M., Molina, S. N., Moritani, Y., Morozova, D. A., Nazarov, S. V., Nikolashvili, M. G., Nilsson, K., Pulatova, N. G., Reinthal, R., Sadun, A., Sasada, M., Savchenko, S. S., Sergeev, S. G., Sigua, L. A., Smith, P. S., Sorcia, M., Spiridonova, O. I., Takaki, K., Takalo, L. O., Taylor, B., Troitsky, I. S., Uemura, M., Ugolkova, L. S., Ui, T., Yoshida, M., Zensus, J. A., and Zhdanova, V. E.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Over the past few years, several occasions of large, continuous rotations of the electric vector position angle (EVPA) of linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy gamma-ray flares and they have attracted considerable attention, as they could allow one to probe the magnetic field structure in the gamma-ray emitting region of the jet. The flat-spectrum radio quasar 3C279 is one of the most prominent examples showing this behaviour. Our goal is to study the observed EVPA rotations and to distinguish between a stochastic and a deterministic origin of the polarization variability. We have combined multiple data sets of R-band photometry and optical polarimetry measurements of 3C279, yielding exceptionally well-sampled flux density and polarization curves that cover a period of 2008-2012. Several large EVPA rotations are identified in the data. We introduce a quantitative measure for the EVPA curve smoothness, which is then used to test a set of simple random walk polarization variability models against the data. 3C279 shows different polarization variation characteristics during an optical low-flux state and a flaring state. The polarization variation during the flaring state, especially the smooth approx. 360 degrees rotation of the EVPA in mid-2011, is not consistent with the tested stochastic processes. We conclude that during the two different optical flux states, two different processes govern the polarization variation, possibly a stochastic process during the low-brightness state and a deterministic process during the flaring activity., Comment: 19 pages, 15 figures, 6 tables

Published
2016
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25. Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013

Author

Baloković, M., Paneque, D., Madejski, G., Furniss, A., Chiang, J., team, the NuSTAR, Ajello, M., Alexander, D. M., Barret, D., Blandford, R., Boggs, S. E., Christensen, F. E., Craig, W. W., Forster, K., Giommi, P., Grefenstette, B. W., Hailey, C. J., Harrison, F. A., Hornstrup, A., Kitaguchi, T., Koglin, J. E., Madsen, K. K., Mao, P. H., Miyasaka, H., Mori, K., Perri, M., Pivovaroff, M. J., Puccetti, S., Rana, V., Stern, D., Tagliaferri, G., Urry, C. M., Westergaard, N. J., Zhang, W. W., Zoglauer, A., collaboration, the VERITAS, Archambault, S., Archer, A. A., Barnacka, A., Benbow, W., Bird, R., Buckley, J., Bugaev, V., Cerruti, M., Chen, X., Ciupik, L., Connolly, M. P., Cui, W., Dickinson, H. J., Dumm, J., Eisch, J. D., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Fortson, L., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Huetten, M., Haakansson, N., Holder, J., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Maier, G., McArthur, S., Meagher, K., Moriarty, P., Nelson, T., Nieto, D., Ong, R. A., Park, N., Pohl, M., Popkow, A., Pueschel, E., Reynolds, P. T., Richards, G. T., Roache, E., Santander, M., Sembroski, G. H., Shahinyan, K., Smith, A. W., Staszak, D., Telezhinsky, I., Todd, N. W., Tucci, J. V., Tyler, J., Vincent, S., Weinstein, A., Wilhelm, A., Williams, D. A., Zitzer, B., collaboration, the MAGIC, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., de Angelis, A., De Lotto, B., Wilhelmi, E. D. de Oña, Mendez, C. Delgado, Di Pierro, F., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Eisenacher, D., Godinović, N., Muñoz, A. González, Guberman, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Nievas-Rosillo, M., Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palacio, S., Palatiello, M., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Saito, T., Satalecka, K., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L. O., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., collaborators, external, Perkins, J., Verrecchia, F., Leto, C., Böttcher, M., Villata, M., Raiteri, C. M., Acosta-Pulido, J. A., Bachev, R., Berdyugin, A., Blinov, D. A., Carnerero, M. I., Chen, W. P., Chinchilla, P., Damljanovic, G., Eswaraiah, C., Grishina, T. S., Ibryamov, S., Jordan, B., Jorstad, S. G., Joshi, M., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Larionov, V. M., Latev, G., Lin, H. C., Marscher, A. P., Mokrushina, A. A., Morozova, D. A., Nikolashvili, M. G., Semkov, E., Strigachev, A., Troitskaya, Yu. V., Troitsky, I. S., Vince, O., Barnes, J., Güver, T., Moody, J. W., Sadun, A. C., Sun, S., Hovatta, T., Richards, J. L., Max-Moerbeck, W., Readhead, A. C., Lähteenmäki, A., Tornikoski, M., Tammi, J., Ramakrishnan, V., Reinthal, R., Angelakis, E., Fuhrmann, L., Myserlis, I., Karamanavis, V., Sievers, A., Ungerechts, H., and Zensus, J. A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present coordinated multiwavelength observations of the bright, nearby BL Lac object Mrk 421 taken in 2013 January-March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from radio to very-high-energy (VHE) gamma-ray bands. NuSTAR yielded previously unattainable sensitivity in the 3-79 keV range, revealing that the spectrum softens when the source is dimmer until the X-ray spectral shape saturates into a steep power law with a photon index of approximately 3, with no evidence for an exponential cutoff or additional hard components up to about 80 keV. For the first time, we observed both the synchrotron and the inverse-Compton peaks of the spectral energy distribution (SED) simultaneously shifted to frequencies below the typical quiescent state by an order of magnitude. The fractional variability as a function of photon energy shows a double-bump structure which relates to the two bumps of the broadband SED. In each bump, the variability increases with energy which, in the framework of the synchrotron self-Compton model, implies that the electrons with higher energies are more variable. The measured multi-band variability, the significant X-ray-to-VHE correlation down to some of the lowest fluxes ever observed in both bands, the lack of correlation between optical/UV and X-ray flux, the low degree of polarization and its significant (random) variations, the short estimated electron cooling time, and the significantly longer variability timescale observed in the NuSTAR light curves point toward in-situ electron acceleration, and suggest that there are multiple compact regions contributing to the broadband emission of Mrk 421 during low-activity states., Comment: 32 pages, 14 figures; accepted for publication in ApJ

Published
2015
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26. First NuSTAR Observations of Mrk 501 within a Radio to TeV Multi-Instrument Campaign

Author

Furniss, A., Noda, K., Boggs, S., Chiang, J., Christensen, F., Craig, W., Giommi, P ., Hailey, C., Harisson, F., Madejski, G., Nalewajko, K., Perri, M., Stern, D., Urry, M., Verrecchia, F., Zhang, W., Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., Gonzalez, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Wilhelmi, E. de Ona, Mendez, C. Delgado, Di Pierro, F., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Glawion, D. Eisenacher, Elsaesser, D., Fernandez-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., Lopez, R. J. Garcia, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Godinovic, N., Munoz, A. Gonzalez, Guberman, D., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kellermann, H., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Lorenz, E., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martinez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Nakajima, D., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nilsson, K., Nishijima, K., Orito, R., Overkemping, A., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Garcia, J. Rodriguez, Saito, T., Saito, K., Satalecka, K., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpaa, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Will, M., Zanin, R., Archer, A., Benbow, W., Bird, R., Biteau, J., Bugaev, V., Cardenzana, J. V, Cerruti, M., Chen, X., Ciupik, L., Connolly, M. P., Cui, W., Dickinson, H. J., Dumm, J., Eisch, J. D., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Fortin, P., Fortson, L., Gerard, L., Gillanders, G. H., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Haakansson, N., Holder, J., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Lin, T. T. Y., Maier, G., McArthur, S., McCann, A., Meagher, K., Moriarty, P., Mukherjee, R., Nieto, D., de Bhroithe, A. O'Faolain, Ong, R. A., Park, N., Petry, D., Pohl, M., Popkow, A., Ragan, K., Ratliff, G., Reyes, L. C., Reynolds, P. T., Richards, G. T., Roache, E., Santander, M., Sembroski, G. H., Shahinyan, K., Staszak, D., Telezhinsky, I., Tucci, J. V., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weiner, O. M., Weinstein, A., Wilhelm, A., Williams, D. A., Zitzer, B., Fuhrmann, O. Vince L., Angelakis, E., Karamanavis, V., Myserlis, I., Krichbaum, T. P., Zensus, J. A., Ungerechts, H., Sievers, A., Bachev, R., Bottcher, M., Chen, W. P., Damljanovic, G., Eswaraiah, C., Guver, T., Hovatta, T., Hughes, Z., Ibryamov, S. . I., Joner, M. D., Jordan, B., Jorstad, S. G., Joshi, M., Kataoka, J., Kurtanidze, O. M., Kurtanidze, S. O., Lahteenmaki, A., Latev, G., Lin, H. C., Larionov, V. M., Mokrushina, A. A., Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Ramakrishnan, V., Readhead, A. C. R., Sadun, A. C., Sigua, L. A., Semkov, E. H., Strigachev, A., Tammi, J., Tornikoski, M., Troitsky, Y. V. Troitskaya I. S., and Villata, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 1 April and 10 August 2013, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. During the campaign, the nearby BL Lac object was observed in both a quiescent and an elevated state. The broadband campaign includes observations with NuSTAR, MAGIC, VERITAS, the Fermi Large Area Telescope (LAT), Swift X-ray Telescope and UV Optical Telescope, various ground-based optical instruments, including the GASP-WEBT program, as well as radio observations by OVRO, Mets\"ahovi and the F-Gamma consortium. Some of the MAGIC observations were affected by a sand layer from the Saharan desert, and had to be corrected using event-by-event corrections derived with a LIDAR (LIght Detection And Ranging) facility. This is the first time that LIDAR information is used to produce a physics result with Cherenkov Telescope data taken during adverse atmospheric conditions, and hence sets a precedent for the current and future ground-based gamma-ray instruments. The NuSTAR instrument provides unprecedented sensitivity in hard X-rays, showing the source to display a spectral energy distribution between 3 and 79 keV consistent with a log-parabolic spectrum and hard X-ray variability on hour timescales. None (of the four extended NuSTAR observations) shows evidence of the onset of inverse-Compton emission at hard X-ray energies. We apply a single-zone equilibrium synchrotron self-Compton model to five simultaneous broadband spectral energy distributions. We find that the synchrotron self-Compton model can reproduce the observed broadband states through a decrease in the magnetic field strength coinciding with an increase in the luminosity and hardness of the relativistic leptons responsible for the high-energy emission., Comment: Accepted for publication in ApJ

Published
2015
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27. Optical and Radio Variability of BL Lacertae

Author

Gaur, Haritma, Gupta, Alok C., Bachev, R., Strigachev, A., Semkov, E., Wiita, Paul J., Volvach, A. E., Gu, Minfeng, Agarwal, A., Agudo, I., Aller, M. F., Aller, H. D., Kurtanidze, O. M., Kurtanidze, S. O., Lahteenmaki, A., Peneva, S., Nikolashvili, M. G., Sigua, L. A., Tornikoski, M., and Volvach, L. N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We observed the prototype blazar, BL Lacertae, extensively in optical and radio bands during an active phase in the period 2010--2013 when the source showed several prominent outbursts. We searched for possible correlations and time lags between the optical and radio band flux variations using multifrequency data to learn about the mechanisms producing variability. During an active phase of BL Lacertae, we searched for possible correlations and time lags between multifrequency light curves of several optical and radio bands. We tried to estimate any possible variability timescales and inter-band lags in these bands. We performed optical observations in B, V, R and I bands from seven telescopes in Bulgaria, Georgia, Greece and India and obtained radio data at 36.8, 22.2, 14.5, 8 and 4.8 GHz frequencies from three telescopes in Ukraine, Finland and USA. Significant cross-correlations between optical and radio bands are found in our observations with a delay of cm-fluxes with respect to optical ones of ~250 days. The optical and radio light curves do not show any significant timescales of variability. BL Lacertae showed many optical 'mini-flares' on short time-scales. Variations on longer term timescales are mildly chromatic with superposition of many strong optical outbursts. In radio bands, the amplitude of variability is frequency dependent. Flux variations at higher radio frequencies lead the lower frequencies by days or weeks. The optical variations are consistent with being dominated by a geometric scenario where a region of emitting plasma moves along a helical path in a relativistic jet. The frequency dependence of the variability amplitude supports an origin of the observed variations intrinsic to the source., Comment: 10 pages, 9 figures, Accepted for publication in A&A

Published
2015
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28. Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010

Author

The MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Boller, A., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Wilhelmi, E. de Oña, Mendez, C. Delgado, Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hanabata, Y., Hayashida, M., Herrera, J., Hildebrand, D., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saito, T., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Sun, S., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Steinke, B., Storz, J., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Zanin, R., Collaboration, The VERITAS, Archambault, S., Archer, A., Beilicke, M., Benbow, W., Berger, K., Bird, R., Biteau, J., Buckley, J. H., Bugaev, V., Cerruti, M., Chen, X., Ciupik, L., Collins-Hughes, E., Cui, W., Eisch, J. D., Falcone, A., Feng, Q., Finley, J. P., Fortin, P., Fortson, L., Furniss, A., Galante, N., Gillanders, G. H., Griffin, S., Gyuk, G., Håkansson, N., Holder, J., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Lang, M. J., McArthur, S., McCann, A., Meagher, K., Millis, J., Moriarty, P., Ong, R. A., Otte, A. N., Perkins, J. S., Pichel, A., Pohl, M., Popkow, A., Prokoph, H., Pueschel, E., Ragan, K., Reyes, L. C., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Sembroski, G. H., Shahinyan, K., Staszak, D., Telezhinsky, I., Tucci, J. V., Tyler, J., Varlotta, A., Wakely, S. P., Welsing, R., Wilhelm, A., Williams, D. A., Collaborators, External, Buson, S., Finke, J., Villata, M., Raiteri, C., Aller, H. D., Aller, M. F., Cesarini, A., Chen, W. P., Gurwell, M. A., Jorstad, S. G., Kimeridze, G. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Lin, H. C., McBreen, B., Moody, J. W., Morozova, D. A., Marscher, A. P., Max-Moerbeck, W., Nikolashvili, M. G., Perri, M., Readhead, A. C. S., Richards, J. L., Ros, J. A., Sadun, A. C., Sakamoto, T., Sigua, L. A., Smith, P. S., Tornikoski, M., Troitsky, I. S., Wehrle, A. E., and Jordan, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

A flare from the TeV blazar Mrk 421, occurring in March 2010, was observed for 13 consecutive days from radio to very high energy (VHE, E > 100 GeV) gamma-rays with MAGIC, VERITAS, Whipple, FermiLAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We model the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigate the physical parameters, and evaluate whether the observed broadband SED variability can be associated to variations in the relativistic particle population. Flux variability was remarkable in the X-ray and VHE bands while it was minor or not significant in the other bands. The one-zone SSC model can describe reasonably well the SED of each day for the 13 consecutive days. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission while the other smaller zone, which is spatially separated from the first one, contributes to the daily-variable emission occurring in X-rays and VHE gamma-rays. Both the one-zone SSC and the two-zone SSC models can describe the daily SEDs via the variation of only four or five model parameters, under the hypothesis that the variability is associated mostly to the underlying particle population. This shows that the particle acceleration and cooling mechanism producing the radiating particles could be the main one responsible for the broadband SED variations during the flaring episodes in blazars. The two-zone SSC model provides a better agreement to the observed SED at the narrow peaks of the low- and high-energy bumps during the highest activity, although the reported one-zone SSC model could be further improved by the variation of the parameters related to the emitting region itself ($\delta$, $B$ and $R$), in addition to the parameters related to the particle population., Comment: Published in A&A, 30 pages, 15 figures, 6 tables. Online-data: multi-wavelength light curves (data in Fig. 1) and broadband spectral energy distributions (the data in Figs. 6, and B1-B4) are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A22. Corresponding authors: David Paneque (dpaneque@mpp.mpg.de), Shangyu Sun (sysun@mpp.mpg.de), Hajime Takami (takami@post.kek.jp)

Published
2014
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29. MAGIC gamma-ray and multifrequency observations of flat spectrum radio quasar PKS 1510-089 in early 2012

Author

MAGIC Collaboration, Aleksić, J., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Carreto-Fidalgo, D., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Godinović, N., Muñoz, A. González, Gozzini, S. R., Hadasch, D., Hayashida, M., Herrera, J., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Kodani, K., Konno, Y., Krause, J., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Lombardi, S., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar-Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nishijima, K., Noda, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Partini, S., Persic, M., Prada, F., Moroni, P. G. Prada, Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saggion, A., Saito, T., Saito, K., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Strzys, M., Sun, S., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Lucarelli, F., Pittori, C., Vercellone, S., Verrecchia, F., Buson, S., D'Ammando, F., Stawarz, L., Giroletti, M., Orienti, M., Mundell, C., Steele, I., Zarpudin, B., Raiteri, C. M., Villata, M., Sandrinelli, A., Lähteenäki, A., Tammi, J., Tornikoski, M., Hovatta, T., Readhead, A. C. S., Max-Moerbeck, W., Richards, J. L., Jorstad, S., Marscher, A., Gurwell, M. A., Larionov, V. M., Blinov, D. A., Konstantinova, T. S., Kopatskaya, E. N., Larionova, L. V., Larionova, E. G., Morozova, D. A., Troitsky, I. S., Mokrushina, A. A., Pavlova, Yu. V., Chen, W. P., Lin, H. C., Panwar, N., Agudo, I., Casadio, C., Gómez, J. L., Molina, S. N., Kurtanidze, O. M., Nikolashvili, M. G., Kurtanidze, S. O., Chigladze, R. A., Acosta-Pulido, J. A., Carnerero, M. I., Manilla-Robles, A., Ovcharov, E., Bozhilov, V., Metodieva, I., Aller, M. F., Aller, H. D., Fuhrmann, L., Angelakis, E., Nestoras, I., Krichbaum, T. P., Zensus, J. A., Ungerechts, H., Sievers, A., and Riquelme, D.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Among more than fifty blazars detected in very high energy (VHE, E>100GeV) gamma-rays, only three belong to the subclass of Flat Spectrum Radio Quasars (FSRQs). MAGIC observed FSRQ PKS 1510-089 in February-April 2012 during a high activity state in the high energy (HE, E>100 MeV) gamma-ray band observed by AGILE and Fermi. MAGIC observations result in the detection of a source with significance of 6.0 sigma. In agreement with the previous VHE observations of the source, we find no statistically significant variability during the MAGIC observations in daily, weekly or monthly time scales. The other two known VHE FSRQs have shown daily scale to sub-hour variability. We study the multifrequency behaviour of the source at the epoch of MAGIC observation, collecting quasi-simultaneous data at radio and optical (GASP-WEBT and F-Gamma collaborations, REM, Steward, Perkins, Liverpool, OVRO and VLBA telescopes), X-ray (Swift satellite) and HE gamma-ray frequencies. The gamma-ray SED combining AGILE, Fermi and MAGIC data joins smoothly and shows no hint of a break. The multifrequency light curves suggest a common origin for the millimeter radio and HE gamma-ray emission and the HE gamma-ray flaring starts when the new component is ejected from the 43GHz VLBA core. The quasi-simultaneous multifrequency SED is modelled with a one-zone inverse Compton model. We study two different origins of the seed photons for the inverse Compton scattering, namely the infra-red torus and a slow sheath surrounding the jet around the VLBA core. Both models fit the data well. However, the fast HE gamma-ray variability requires that within the modelled large emitting region, there must exist more compact regions. We suggest that these observed signatures would be most naturally explained by a turbulent plasma flowing at a relativistic speed down the jet and crossing a standing conical shock., Comment: 21 pages, 15 figures, A&A in press

Published
2014
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30. Analyzing polarization swings in 3C 279

Author

Kiehlmann, S., Savolainen, T., Jorstad, S. G., Sokolovsky, K. V., Schinzel, F. K., Agudo, I., Arkharov, A. A., Benitez, E., Berdyugin, A., Blinov, D. A., Bochkarev, N. G., Borman, G. A., Burenkov, A. N., Casadio, C., Doroshenko, V. T., Efimova, N. V., Fukazawa, Y., Gomez, J. L., Hagen-Thorn, V. A., Heidt, J., Hiriart, D., Itoh, R., Joshi, M., Kimeridze, G. N., Konstantinova, T. S., Kopatskaya, E. N., Korobtsev, I. V., Kovalev, Y. Y., Krajci, T., Kurtanidze, O., Kurtanidze, S. O., Larionov, V. M., Larionova, E. G., Larionova, L. V., Lindfors, E., Lopez, J. M., Marscher, A. P., McHardy, I. M., Molina, S. N., Morozova, D. A., Nazarov, S. V., Nikolashvili, M. G., Nilsson, K., Pulatova, N. G., Reinthal, R., Sadun, A., Sergeev, S. G., Sigua, L. A., Sorcia, M., Spiridonova, O. I., Takalo, L. O., Taylor, B., Troitsky, I. S., Ugolkova, L. S., Zensus, J. A., and Zhdanova, V. E.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Quasar 3C 279 is known to exhibit episodes of optical polarization angle rotation. We present new, well-sampled optical polarization data for 3C 279 and introduce a method to distinguish between random and deterministic electric vector position angle (EVPA) variations. We observe EVPA rotations in both directions with different amplitudes and find that the EVPA variation shows characteristics of both random and deterministic cases. Our analysis indicates that the EVPA variation is likely dominated by a random process in the low brightness state of the jet and by a deterministic process in the flaring state., Comment: 6 pages, 2 figures, 4 tables, proceeding to appear on EPJ Web of Conferences "The Innermost Regions of Relativistic Jets and their Magnetic Fields (Granada, Spain,10-14 June 2013)"

Published
2013
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31. Multiwavelength Intraday Variability of the BL Lac S5 0716+714

Author

Gupta, Alok C., Krichbaum, T. P., Wiita, P. J., Rani, B., Sokolovsky, K. V., Mohan, P., Mangalam, A., Marchili, N., Fuhrmann, L., Agudo, I., Bach, U., Bachev, R., Böttcher, M., Gabanyi, K. E., Gaur, H., Hawkins, K., Kimeridze, G. N., Kurtanidze, O. M., Kurtanidze, S. O., Lee, C. -U., Liu, X., McBreen, B., Nesci, R., Nestoras, G., Nikolashvili, M. G., Ohlert, J. M., Palma, N., Peneva, S., Pursimo, T., Semkov, E., Strigachev, A., Webb, J. R., Wiesemeyer, H., and Zensus, J. A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

We report results from a 1 week multi-wavelength campaign to monitor the BL Lac object S5 0716+714 (on December 9-16, 2009). In the radio bands the source shows rapid (~ (0.5-1.5) day) intra-day variability with peak amplitudes of up to ~ 10 %. The variability at 2.8 cm leads by about 1 day the variability at 6 cm and 11 cm. This time lag and more rapid variations suggests an intrinsic contribution to the source's intraday variability at 2.8 cm, while at 6 cm and 11 cm interstellar scintillation (ISS) seems to predominate. Large and quasi-sinusoidal variations of ~ 0.8 mag were detected in the V, R and I-bands. The X-ray data (0.2-10 keV) do not reveal significant variability on a 4 day time scale, favoring reprocessed inverse-Compton over synchrotron radiation in this band. The characteristic variability time scales in radio and optical bands are similar. A quasi-periodic variation (QPO) of 0.9 - 1.1 days in the optical data may be present, but if so it is marginal and limited to 2.2 cycles. Cross-correlations between radio and optical are discussed. The lack of a strong radio-optical correlation indicates different physical causes of variability (ISS at long radio wavelengths, source intrinsic origin in the optical), and is consistent with a high jet opacity and a compact synchrotron component peaking at ~= 100 GHz in an ongoing very prominent flux density outburst. For the campaign period, we construct a quasi-simultaneous spectral energy distribution (SED), including gamma-ray data from the FERMI satellite. We obtain lower limits for the relativistic Doppler-boosting of delta >= 12-26, which for a BL\,Lac type object, is remarkably high., Comment: 16 pages, 15 figures, table 2; Accepted for Publication in MNRAS

Published
2012
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32. Variability of the blazar 4C 38.41 (B3 1633+382) from GHz frequencies to GeV energies

Author

Raiteri, C. M., Villata, M., Smith, P. S., Larionov, V. M., Acosta-Pulido, J. A., Aller, M. F., D'Ammando, F., Gurwell, M. A., Jorstad, S. G., Joshi, M., Kurtanidze, O. M., Lähteenmäki, A., Mirzaqulov, D. O., Agudo, I., Aller, H. D., Arévalo, M. J., Arkharov, A. A., Bach, U., Benítez, E., Berdyugin, A., Blinov, D. A., Blumenthal, K., Buemi, C. S., Bueno, A., Carleton, T. M., Carnerero, M. I., Carosati, D., Casadio, C., Chen, W. P., Di Paola, A., Dolci, M., Efimova, N. V., Ehgamberdiev, Sh. A., Gómez, J. L., Gonzále, A. I., Hagen-Thorn, V. A., Heidt, J., Hiriart, D., Holikov, Sh., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., León-Tavares, J., Leto, P., Lin, H. C., Lindfors, E., Marscher, A. P., McHardy, I. M., Molina, S. N., Morozova, D. A., Mujica, R., Nikolashvili, M. G., Nilsson, K., Ovcharov, E. P., Panwar, N., Pasanen, M., Puerto-Gimenez, I., Reinthal, R., Richter, G. M., Ros, J. A., Sakamoto, T., Schwartz, R. D., Sillanpää, A., Smith, N., Takalo, L. O., Tammi, J., Taylor, B., Thum, C., Tornikoski, M., Trigilio, C., Troitsky, I. S., Umana, G., Valcheva, A. T., and Wehrle, A. E.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum. We present the results of low-energy multifrequency monitoring by the GASP project of the WEBT consortium and collaborators, as well as those of spectropolarimetric/spectrophotometric monitoring at the Steward Observatory. We also analyse high-energy observations of the Swift and Fermi satellites. In the optical-UV band, several results indicate that there is a contribution from a QSO-like emission component, in addition to both variable and polarised jet emission. The unpolarised emission component is likely thermal radiation from the accretion disc that dilutes the jet polarisation. We estimate its brightness to be R(QSO) ~ 17.85 - 18 and derive the intrinsic jet polarisation degree. We find no clear correlation between the optical and radio light curves, while the correlation between the optical and \gamma-ray flux apparently fades in time, likely because of an increasing optical to \gamma-ray flux ratio. As suggested for other blazars, the long-term variability of 4C 38.41 can be interpreted in terms of an inhomogeneous bent jet, where different emitting regions can change their alignment with respect to the line of sight, leading to variations in the Doppler factor \delta. Under the hypothesis that in the period 2008-2011 all the \gamma-ray and optical variability on a one-week timescale were due to changes in \delta, this would range between ~ 7 and ~ 21. If the variability were caused by changes in the viewing angle \theta\ only, then \theta\ would go from ~ 2.6 degr to ~ 5 degr. Variations in the viewing angle would also account for the dependence of the polarisation degree on the source brightness in the framework of a shock-in-jet model., Comment: 19 pages, 23 figures, in press for Astronomy and Astrophysics

Published
2012
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33. Identification of gamma-ray emission from 3C345 and NRAO512

Author

Schinzel, F. K., Sokolovsky, K. V., D'Ammando, F., Burnett, T. H., Max-Moerbeck, W., Cheung, C. C., Fegan, S. J., Casandjian, J. M., Reyes, L. C., Villata, M., Raiteri, C. M., Agudo, I., Calle, O. J. A. Bravo, Carosati, D., Casas, R., Gomez, J. L., Gurwell, M. A., Hsiao, H. Y., Jorstad, S. G., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Larionov, V. M., Larionova, E. G., Larionova, L. V., Marscher, A. P., Morozova, D. A., Nikolashvili, M. G., Roca-Sogorb, M., Ros, J. A., Sigua, L. A., Spiridonova, O., Troitsky, I. S., Vlasyuk, V. V., Lobanov, A. P., and Zensus, J. A.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

For more than 15 years, since the days of the Energetic Gamma-Ray Experiment Telescope (EGRET) on board the Compton Gamma-Ray Observatory (CGRO; 1991-2000), it has remained an open question why the prominent blazar 3C 345 was not reliably detected at gamma-ray energies <=20 MeV. Recently a bright gamma-ray source (0FGL J1641.4+3939/1FGL J1642.5+3947), potentially associated with 3C 345, was detected by the Large Area Telescope (LAT) on Fermi. Multiwavelength observations from radio bands to X-rays (mainly GASP-WEBT and Swift) of possible counterparts (3C 345, NRAO 512, B3 1640+396) were combined with 20 months of Fermi-LAT monitoring data (August 2008 - April 2010) to associate and identify the dominating gamma-ray emitting counterpart of 1FGL J1642.5+3947. The source 3C 345 is identified as the main contributor for this gamma-ray emitting region. However, after November 2009 (15 months), a significant excess of photons from the nearby quasar NRAO 512 started to contribute and thereafter was detected with increasing gamma-ray activity, possibly adding flux to 1FGL J1642.5+3947. For the same time period and during the summer of 2010, an increase of radio, optical and X-ray activity of NRAO 512 was observed. No gamma-ray emission from B3 1640+396 was detected., Comment: 11 pages, 5 figures, 5 tables, accepted for publication in A&A

Published
2011
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34. The brightest gamma-ray flaring blazar in the sky: AGILE and multi-wavelength observations of 3C 454.3 during November 2010

Author

Vercellone, S., Striani, E., Vittorini, V., Donnarumma, I., Pacciani, L., Pucella, G., Tavani, M., Raiteri, C. M., Villata, M., Romano, P., Fiocchi, M., Bazzano, A., Bianchin, V., Ferrigno, C., Maraschi, L., Pian, E., Türler, M., Ubertini, P., Bulgarelli, A., Chen, A. W., Giuliani, A., Longo, F., Barbiellini, G., Cardillo, M., Cattaneo, P. W., Del Monte, E., Evangelista, Y., Feroci, M., Ferrari, A., Fuschino, F., Gianotti, F., Giusti, M., Lazzarotto, F., Pellizzoni, A., Piano, G., Pilia, M., Rapisarda, M., Rappoldi, A., Sabatini, S., Soffitta, P., Trifoglio, M., Trois, A., Giommi, P., Lucarelli, F., Pittori, C., Santolamazza, P., Verrecchia, F., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Berdyugin, A., Borman, G. A., Chigladze, R., Efimov, Yu. S., Efimova, N. V., Gómez, J. L., Gurwell, M. A., McHardy, I. M., Joshi, M., Kimeridze, G. N., Krajci, T., Kurtanidze, O. M., Kurtanidze, S. O., Larionov, V. M., Lindfors, E., Molina, S. N., Morozova, D. A., Nazarov, S. V., Nikolashvili, M. G., Nilsson, K., Pasanen, M., Reinthal, R., Ros, J. A., Sadun, A. C., Sakamoto, T., Sallum, S., Sergeev, S. G., Schwartz, R. D., Sigua, L. A., Sillanpää, A., Sokolovsky, K. V., Strelnitski, V., Takalo, L., Taylor, B., and Walker, G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all frequencies, and during the last four years it has exhibited more than one gamma-ray flare per year, becoming the most active gamma-ray blazar in the sky. We present for the first time the multi-wavelength AGILE, SWIFT, INTEGRAL, and GASP-WEBT data collected in order to explain the extraordinary gamma-ray flare of 3C 454.3 which occurred in November 2010. On 2010 November 20 (MJD 55520), 3C 454.3 reached a peak flux (E>100 MeV) of F_gamma(p) = (6.8+-1.0)E-5 ph/cm2/s on a time scale of about 12 hours, more than a factor of 6 higher than the flux of the brightest steady gamma-ray source, the Vela pulsar, and more than a factor of 3 brighter than its previous super-flare on 2009 December 2-3. The multi-wavelength data make a thorough study of the present event possible: the comparison with the previous outbursts indicates a close similarity to the one that occurred in 2009. By comparing the broadband emission before, during, and after the gamma-ray flare, we find that the radio, optical and X-ray emission varies within a factor 2-3, whereas the gamma-ray flux by a factor of 10. This remarkable behavior is modeled by an external Compton component driven by a substantial local enhancement of soft seed photons., Comment: Accepted for publication in ApJ Letters. 18 Pages, 4 Figures, 1 Table

Published
2011
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35. AGILE detection of extreme gamma-ray activity from the blazar PKS 1510-089 during March 2009. Multifrequency analysis

Author

D'Ammando, F., Raiteri, C. M., Villata, M., Romano, P., Pucella, G., Krimm, H. A., Covino, S., Orienti, M., Giovannini, G., Vercellone, S., Pian, E., Donnarumma, I., Vittorini, V., Tavani, M., Argan, A., Barbiellini, G., Boffelli, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, A. W., Cocco, V., Costa, E., Del Monte, E., De Paris, G., Di Cocco, G., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Froysland, T., Frutti, M., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Marisaldi, M., Mereghetti, S., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Striani, E., Trifoglio, M., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Benitez, E., Berdyugin, A., Blinov, D. A., Buemi, C. S., Chen, W. P., Di Paola, A., Dolci, M., Forne, E., Fuhrmann, L., Gomez, J. L., Gurwell, M. A., Jordan, B., Jorstad, S. G., Heidt, J., Hiriart, D., Hovatta, T., Hsiao, H. Y., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Larionov, V. M., Lahteenmaki, A., Leto, P., Lindfors, E., Marscher, A. P., McBreen, B., McHardy, I. M., Morozova, D. A., Nilsson, K., Pasanen, M., Roca-Sogorb, M., Sillanpaa, A., Takalo, L. O., Tornikoski, M., Trigilio, C., Troitsky, I. S., Umana, G., Antonelli, L. A., Colafrancesco, S., Pittori, C., Santolamazza, P., Verrecchia, F., Giommi, P., and Salotti, L.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the extreme gamma-ray activity from the FSRQ PKS 1510-089 observed by AGILE in March 2009. In the same period a radio-to-optical monitoring of the source was provided by the GASP-WEBT and REM. Moreover, several Swift ToO observations were triggered, adding important information on the source behaviour from optical/UV to hard X-rays. We paid particular attention to the calibration of the Swift/UVOT data to make it suitable to the blazars spectra. Simultaneous observations from radio to gamma rays allowed us to study in detail the correlation among the emission variability at different frequencies and to investigate the mechanisms at work. In the period 9-30 March 2009, AGILE detected an average gamma-ray flux of (311+/-21)x10^-8 ph cm^-2 s^-1 for E>100 MeV, and a peak level of (702+/-131)x10^-8 ph cm^-2 s^-1 on daily integration. The gamma-ray activity occurred during a period of increasing activity from near-IR to UV, with a flaring episode detected on 26-27 March 2009, suggesting that a single mechanism is responsible for the flux enhancement observed from near-IR to UV. By contrast, Swift/XRT observations seem to show no clear correlation of the X-ray fluxes with the optical and gamma-ray ones. However, the X-ray observations show a harder photon index (1.3-1.6) with respect to most FSRQs and a hint of harder-when-brighter behaviour, indicating the possible presence of a second emission component at soft X-ray energies. Moreover, the broad band spectrum from radio-to-UV confirmed the evidence of thermal features in the optical/UV spectrum of PKS 1510-089 also during high gamma-ray state. On the other hand, during 25-26 March 2009 a flat spectrum in the optical/UV energy band was observed, suggesting an important contribution of the synchrotron emission in this part of the spectrum during the brightest gamma-ray flare, therefore a significant shift of the synchrotron peak., Comment: 13 pages, 7 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics

Published
2011
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36. Multiwavelength Observations of the Blazar VER J0521+211 during an Elevated TeV Gamma-Ray State

Author

Abe, H., Abe, S., Acciari, V. A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., Barres de Almeida, U., Barrio, J. A., Batković, I., Baxter, J., Becerra González, J., Bednarek, W., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Burelli, I., Busetto, G., Carosi, R., Carretero-Castrillo, M., Castro-Tirado, A. J., Ceribella, G., Chai, Y., Chilingarian, A., Cikota, S., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Popolo, A., Delfino, M., Delgado, J., Delgado Mendez, C., Depaoli, D., Di Pierro, F., Di Venere, L., Do Souto Espiñeira, E., Dominis Prester, D., Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., Fallah Ramazani, V., Fariña, L., Fattorini, A., Foffano, L., Font, L., Fruck, C., Fukami, S., Fukazawa, Y., García López, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Giesbrecht Paiva, J. G., Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Grau, R., Green, D., Green, J. G., Hadasch, D., Hahn, A., Hassan, T., Heckmann, L., Herrera, J., Hrupec, D., Hütten, M., Imazawa, R., Inada, T., Iotov, R., Ishio, K., Jiménez Martínez, I., Jormanainen, J., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Lyard, E., Machado de Oliveira Fraga, B., Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mangano, S., Mannheim, K., Mariotti, M., Martínez, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Moreno, V., Nakamori, T., Nanci, C., Nava, L., Neustroev, V., Nievas Rosillo, M., Nigro, C., Nilsson, K., Nishijima, K., Njoh Ekoume, T., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Prada Moroni, P. G., Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sitarek, J., Sliusar, V., Sobczynska, D., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Tajima, H., Takahashi, M., Takeishi, R., Tavecchio, F., Temnikov, P., Terauchi, K., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Vazquez Acosta, M., Ventura, S., Verguilov, V., Viale, I., Vigorito, C. F., Vitale, V., Vovk, I., Walter, R., Will, M., Wunderlich, C., Yamamoto, T., Zarić, D., Other, Groups, Cerruti, collaborations: M., Acosta-Pulido, J. A., Apolonio, G., Bachev, R., Baloković, M., Benítez, E., Björklund, I., Bozhilov, V., Brown, L. F., Bugg, A., Carbonell, W., Carnerero, M. I., Carosati, D., Casadio, C., Chamani, W., Chen, W. P., Chigladze, R. A., Damljanovic, G., Epps, K., Erkenov, A., Feige, M., Finke, J., Fuentes, A., Gazeas, K., Giroletti, M., Grishina, T. S., Gupta, A. C., Gurwell, M. A., Heidemann, E., Hiriart, D., Hou, W. J., Hovatta, T., Ibryamov, S., Joner, M. D., Jorstad, S. G., Kania, J., Kiehlmann, S., Kimeridze, G. N., Kopatskaya, E. N., Kopp, M., Korte, M., Kotas, B., Koyama, S., Kramer, J. A., Kunkel, L., Kurtanidze, S. O., Kurtanidze, O. M., Lähteenmäki, A., López, J. M., Larionov, V. M., Larionova, E. G., Larionova, L. V., Leto, C., Lorey, C., Mújica, R., Madejski, G. M., Marchili, N., Marscher, A. P., Minev, M., Modaressi, A., Morozova, D. A., Mufakharov, T., Myserlis, I., Nikiforova, A. A., Nikolashvili, M. G., Ovcharov, E., Perri, M., Raiteri, C. M., Readhead, A. C. S., Reimer, A., Reinhart, D., Righini, S., Rosenlehner, K., Sadun, A. C., Savchenko, S. S., Scherbantin, A., Schneider, L., Schoch, K., Seifert, D., Semkov, E., Sigua, L. A., Singh, C., Sola, P., Sotnikova, Y., Spencer, M., Steineke, R., Stojanovic, M., Strigachev, A., Tornikoski, M., Traianou, E., Tramacere, A., Troitskaya, Yu. V., Troitskiy, I. S., Trump, J. B., Tsai, A., Valcheva, A., Vasilyev, A. A., Verrecchia, F., Villata, M., Vince, O., Vrontaki, K., Weaver, Z. R., Zaharieva, E., Zottmann, N., Ministerio de Ciencia e Innovación (España), European Commission, Federal Ministry of Education and Research (Germany), Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Astrofisica, Swiss National Science Foundation, Department of Atomic Energy (India), Ministry of Education, Culture, Sports, Science and Technology (Japan), Ministry of Education and Science (Bulgaria), and Academy of Finland

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), BL Lacertae objects: individual (VER J0521+211 = RGB J0521.8+2112) – galaxies: active – galaxies: jets – gamma rays: galaxies – radiation mechanisms: non-thermal, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Active galactic nuclei, High energy astrophysics, Blazars, BL Lacertae objects, Relativistic jets, Gamma-rays, Non-thermal radiation sources, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), ddc:520, Física nuclear, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Full list of authors: Adams, C. B.; Batista, P.; Benbow, W.; Brill, A.; Brose, R.; Buckley, J. H.; Capasso, M.; Christiansen, J. L.; Errando, M.; Feng, Q.; Finley, J. P.; Foote, G. M.; Fortson, L.; Furniss, A.; Gallagher, G.; Gent, A.; Giuri, C.; Hanlon, W. F.; Hanna, D.; Hassan, T.; Hervet, O.; Holder, J.; Hona, B.; Hughes, G.; Humensky, T. B.; Jin, W.; Kaaret, P.; Kertzman, M.; Kieda, D.; Kleiner, T. K.; Krennrich, F.; Kumar, S.; Lang, M. J.; Lundy, M.; Maier, G.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nievas-Rosillo, M.; Ong, R. A.; Otte, A. N.; Patel, S.; Patel, S. R.; Pfrang, K.; Pohl, M.; Prado, R. R.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Ribeiro, D.; Roache, E.; Ryan, J. L.; Sadeh, I; Santander, M.; Sembroski, G. H.; Shang, R.; Stevenson, B.; Tucci, J., V; Vassiliev, V. V.; Wakely, S. P.; Weinstein, A.; Wells, R. M.; Williams, D. A.; Williamson, T. J.; Acciari, V. A.; Aniello, T.; Ansoldi, S.; Antonelli, L. A.; Engels, A. Arbet; Arcaro, C.; Artero, M.; Asano, K.; Baack, D.; Babic, A.; Baquero, A.; de Almeida, U. Barres; Barrio, J. A.; Batkovic, I; Becerra Gonzalez, J.; Bednarek, W.; Bernardini, E.; Bernardos, M.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bokenkamp, H.; Bonnoli, G.; Bosnjak, Z.; Burelli, I; Busetto, G.; Carosi, R.; Ceribella, G.; Cerruti, M.; Chai, Y.; Chilingarian, A.; Cikota, S.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; Del Popolo, A.; Delfino, M.; Delgado, J.; Delgado Mendez, C.; Depaoli, D.; Di Pierro, F.; Di Venere, L.; Do Souto Espineira, E.; Prester, D. Dominis; Donini, A.; Dorner, D.; Doro, M.; Elsaesser, D.; Ramazani, V. Fallah; Farina, L.; Fattorini, A.; Font, L.; Fruck, C.; Fukami, S.; Fukazawa, Y.; Garcia Lopez, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giglietto, N.; Giordano, F.; Gliwny, P.; Godinovic, N.; Green, J. G.; Green, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Heckmann, L.; Herrera, J.; Hrupec, D.; Hutten, M.; Inada, T.; Iotov, R.; Ishio, K.; Iwamura, Y.; Jimenez Martinez, I; Jormanainen, J.; Jouvin, L.; Kerszberg, D.; Kobayashi, Y.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Linhoff, L.; Lombardi, S.; Longo, F.; Lopez-Coto, R.; Lopez-Moya, M.; Lopez-Oramas, A.; Loporchio, S.; Lorini, A.; de Oliveira Fraga, B. Machado; Maggio, C.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Mariotti, M.; Martinez, M.; Aguilar, A. Mas; Mazin, D.; Menchiari, S.; Mender, S.; Micanovic, S.; Miceli, D.; Miener, T.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Mondal, H. A.; Moralejo, A.; Morcuende, D.; Moreno, V; Nakamori, T.; Nanci, C.; Nava, L.; Neustroev, V; Nievas Rosillo, M.; Nigro, C.; Nilsson, K.; Nishijima, K.; Noda, K.; Nozaki, S.; Ohtani, Y.; Oka, T.; Otero-Santos, J.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pavletic, L.; Penil, P.; Persic, M.; Pihet, M.; Moroni, P. G. Prada; Prandini, E.; Priyadarshi, C.; Puljak, I; Rhode, W.; Ribo, M.; Rico, J.; Righi, C.; Rugliancich, A.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Saturni, F. G.; Schleicher, B.; Schmidt, K.; Schmuckermaier, F.; Schubert, J. L.; Schweizer, T.; Sitarek, J.; Snidaric, I; Sobczynska, D.; Spolon, A.; Stamerra, A.; Striskovic, J.; Strom, D.; Strzys, M.; Suda, Y.; Suric, T.; Takahashi, M.; Takeishi, R.; Tavecchio, F.; Temnikov, P.; Terzic, T.; Teshima, M.; Tosti, L.; Truzzi, S.; Tutone, A.; Ubach, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Ventura, S.; Verguilov, V.; Viale, I; Vigorito, C. F.; Vitale, V.; Vovk, I; Will, M.; Wunderlich, C.; Yamamoto, T.; Zaric, D.; VERITAS Collaboration; MAGIC Collaboration.--This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly binned light curve is (8.8 ± 0.4) × 10−7 photons m−2 s−1, or ∼37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be z ≤ 0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED and the radio morphology of the jet from the MOJAVE program are consistent with the source being an intermediate-frequency-peaked BL Lac object. © 2022. The Author(s). Published by the American Astronomical Society., This research is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, and the Smithsonian Institution in the U.S.; by NSERC in Canada; and by the Helmholtz Association in Germany. This research used resources provided by the Open Science Grid, which is supported by the National Science Foundation and the U.S. Department of Energy's Office of Science, and resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under contract No. DE-AC02-05CH11231. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and at the collaborating institutions in the construction and operation of the instrument. The MAGIC Collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF, MPG, and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovación (MICINN) (PID2019-104114RB-C31, PID2019-104114RB-C32, PID2019-104114RB-C33, PID2019-105510GB-C31,PID2019-107847RB-C41, PID2019-107847RB-C42, PID2019-107847RB-C44, PID2019-107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-400/18.12.2020; and the Academy of Finland grant No. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia "Severo Ochoa" (SEV-2016-0588, SEV-2017-0709, CEX2019-000920-S), the Unidad de Excelencia "María de Maeztu" (CEX2019-000918-M, MDM-2015-0509-18-2), and the CERCA program of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project uniri-prirod-18-48; by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3; by the Polish National Research Centre grant UMO-2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq, and FAPERJ. Q.F. was supported by NSF grant PHY-1806554 at Barnard College.

Published
2022
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37. Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution

Author

Nikiforova, A. A., Vasilyev, A. A., Gupta, A. C., Tsai, A. L., Marscher, A. P., Sadun, A., Strigachev, A., Zhovtan, A. V., Valcheva, A., Raiteri, C. M., Morozova, D. A., Carosati, D., Hiriart, D., Dougherty, D. J., Mirzaqulov, D. O., Benitez, E., Larionova, E. G., Kopatskaya, E. N., Evgeni Ovcharov, Semkov, E., Zaharieva, E., Borman, G. A., Damljanovic, G., Kimeridze, G. N., Baida, G. V., Hsiao, H. Y., Troitsky, I. S., Acosta-Pulido, J. A., Slater, J. J., Williamson, K. E., Smith, K. L., Matsumoto, K., Nikolashvili, M. G., Hart, M., Carnerero, M. I., Joner, M., Minev, M., Stojanovic, M., Villata, M., Rizzi, N., Kurtanidze, O. M., Vince, O., Bachev, R., Matsumura, R., Ehgamberdiev, S. A., Jorstad, S. G., Ibryamov, S., Kurtanidze, S. O., Savchenko, S. S., Balonek, T. J., Grishina, T. S., Bozhilov, V., Dhiman, V., Larionov, V. M., Chen, W. P., Troitskaya, Yu V., and Weaver, Zachary R.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations of BL Lacertae over a wide wavelength range: with the \emph{Transiting Exoplanet Survey Satellite} (TESS) at 6,000-10,000 \AA\ with 2-minute cadence; with the Neil Gehrels \emph{Swift} satellite at optical, UV, and X-ray bands; with the Nuclear Spectroscopic Telescope Array at hard X-ray bands; with the \emph{Fermi} Large Area Telescope at $\gamma$-ray energies; and with the Whole Earth Blazar Telescope for measurement of the optical flux density and polarization. All light curves are correlated, with similar structure on timescales from hours to days. The shortest timescale of variability at optical frequencies observed with TESS is $\sim 0.5$ hr. The most common timescale is $13\pm1$~hr, comparable with the minimum timescale of X-ray variability, 14.5 hr. The multi-wavelength variability properties cannot be explained by a change solely in the Doppler factor of the emitting plasma. The polarization behavior implies that there are both ordered and turbulent components to the magnetic field in the jet. Correlation analysis indicates that the X-ray variations lag behind the $\gamma$-ray and optical light curves by up to $\sim 0.4$ days. The timescales of variability, cross-frequency lags, and polarization properties can be explained by turbulent plasma that is energized by a shock in the jet and subsequently loses energy to synchrotron and inverse Compton radiation in a magnetic field of strength $\sim3$ G, Comment: 33 pages, 25 figures, 14 tables. Accepted to ApJ

Published
2020
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38. Multiwavelength study of quiescent states of MRK 421 with unprecedented hard x-ray coverage provided by NuSTAR in 2013

Author

Baloković, M., Paneque, D., Madejski, G., Furniss, A., Chiang, J., the NuSTAR team, Ajello, M., Alexander, D. M., Barret, D., Blandford, R., Boggs, S. E., Christensen, F. E., Craig, W. W., Forster, K., Giommi, P., Grefenstette, B. W., Hailey, C. J., Harrison, F. A., Hornstrup, A., Kitaguchi, T., Koglin, J. E., Madsen, K. K., Mao, P. H., Miyasaka, H., Mori, K., Perri, M., Pivovaroff, M. J., Simonetta Puccetti, Rana, V., Stern, D., Tagliaferri, G., Urry, C. M., Westergaard, N. J., Zhang, W. W., Zoglauer, A., Veritas, The Collaboration, Archambault, S., Archer, A. A., Barnacka, A., Benbow, W., Bird, R., Buckley, J., Bugaev, V., Cerruti, M., Chen, X., Ciupik, L., Connolly, M. P., Cui, W., Dickinson, H. J., Dumm, J., Eisch, J. D., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Fortson, L., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Huetten, M., Haakansson, N., Holder, J., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Maier, G., Mcarthur, S., Meagher, K., Moriarty, P., Nelson, T., Nieto, D., Ong, R. A., Park, N., Pohl, M., Popkow, A., Pueschel, E., Reynolds, P. T., Richards, G. T., Roache, E., Santander, M., Sembroski, G. H., Shahinyan, K., Smith, A. W., Staszak, D., Telezhinsky, I., Todd, N. W., Tucci, J. V., Tyler, J., Vincent, S., Weinstein, A., Wilhelm, A., Williams, D. A., Zitzer, B., Magic, The Collaboration, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., Barres Almeida, U., Barrio, J., Becerra González, J., Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., Angelis, A., Lotto, B., Oña Wilhelmi, E. D., Delgado Mendez, C., Di Pierro, F., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., García López, R. J., Garczarczyk, M., Garrido Terrats, D., Gaug, M., Giammaria, P., Eisenacher, D., Godinović, N., González Muñoz, A., Guberman, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Nievas-Rosillo, M., Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palacio, S., Palatiello, M., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Poutanen, J., Prada Moroni, P. G., Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Rodriguez Garcia, J., Saito, T., Satalecka, K., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L. O., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Collaborators, External, Perkins, J., Verrecchia, F., Leto, C., Böttcher, M., Villata, M., Raiteri, C. M., Acosta-Pulido, J. A., Bachev, R., Berdyugin, A., Blinov, D. A., Carnerero, M. I., Chen, W. P., Chinchilla, P., Damljanovic, G., Eswaraiah, C., Grishina, T. S., Ibryamov, S., Jordan, B., Jorstad, S. G., Joshi, M., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Larionov, V. M., Latev, G., Lin, H. C., Marscher, A. P., Mokrushina, A. A., Morozova, D. A., Nikolashvili, M. G., Semkov, E., Strigachev, A., Troitskaya, Yu V., Troitsky, I. S., Vince, O., Barnes, J., Güver, T., Moody, J. W., Sadun, A. C., Sun, S., Hovatta, T., Richards, J. L., Max-Moerbeck, W., Readhead, A. C., Lähteenmäki, A., Tornikoski, M., Tammi, J., Ramakrishnan, V., Reinthal, R., Angelakis, E., Fuhrmann, L., Myserlis, I., Karamanavis, V., Sievers, A., Ungerechts, H., Zensus, J. A., Universitat de Barcelona, Department of Radio Science and Engineering, Aalto-yliopisto, Aalto University, Glawion , D., ~, Baloković, M., Paneque, D., Madejski, G., Furniss, A., Chiang, J., Ajello, M., Alexander, D. M., Barret, D., Blandford, R. D., Boggs, S. E., Christensen, F. E., Craig, W. W., Forster, K., Giommi, P., Grefenstette, B., Hailey, C., Harrison, F. A., Hornstrup, A., Kitaguchi, T., Koglin, J. E., Madsen, K. K., Mao, P. H., Miyasaka, H., Mori, K., Perri, M., Pivovaroff, M. J., Puccetti, S., Rana, V., Stern, D., Tagliaferri, G., Urry, C. M., Westergaard, N. J., Zhang, W. W., Zoglauer, A., Archambault, S., Archer, A., Barnacka, A., Benbow, W., Bird, R., Buckley, J. H., Bugaev, V., Cerruti, M., Chen, X., Ciupik, L., Connolly, M. P., Cui, W., Dickinson, H. J., Dumm, J., Eisch, J. D., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Fortson, L., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Huetten, M., Håkansson, N., Holder, J., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Maier, G., Mcarthur, S., Meagher, K., Moriarty, P., Nelson, T., Nieto, D., Ong, R. A., Park, N., Pohl, M., Popkow, A., Pueschel, E., Reynolds, P. T., Richards, G. T., Roache, E., Santander, M., Sembroski, G. H., Shahinyan, K., Smith, A. W., Staszak, D., Telezhinsky, I., Todd, N. W., Tucci, J. V., Tyler, J., Vincent, S., Weinstein, A., Wilhelm, A., Williams, D. A., Zitzer, B., Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., De Almeida, U. Barre, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., De Ońa Wilhelmi, E., Mendez, C. Delgado, Di Pierro, F., Prester, D. Domini, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fernández Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Glawion, D., Godinović, N., González Muñoz, A., Guberman, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, Francesco, López, M., López Coto, R., López Oramas, A., Lorenz, E., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nieva, Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palacio, J., Palatiello, Michele, Paoletti, R., Paredes, J. M., Paredes Fortuny, X., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Saito, T., Satalecka, K., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Perkins, J., Verrecchia, F., Leto, C., Böttcher, M., Villata, M., Raiteri, C. M., Acosta Pulido, J. A., Bachev, R., Berdyugin, A., Blinov, D. A., Carnerero, M. I., Chen, W. P., Chinchilla, P., Damljanovic, G., Eswaraiah, C., Grishina, T. S., Ibryamov, S., Jordan, B., Jorstad, S. G., Joshi, M., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Larionov, V. M., Latev, G., Lin, H. C., Marscher, A. P., Mokrushina, A. A., Morozova, D. A., Nikolashvili, M. G., Semkov, E., Smith, P. S., Strigachev, A., Troitskaya, Y. u. V., Troitsky, I. S., Vince, O., Barnes, J., Güver, T., Moody, J. W., Sadun, A. C., Sun, S., Hovatta, T., Richards, J. L., Max Moerbeck, W., Readhead, A. C. R., Lähteenmäki, A., Tornikoski, M., Tammi, J., Ramakrishnan, V., Reinthal, R., Angelakis, E., Fuhrmann, L., Myserlis, I., Karamanavis, V., Sievers, A., Ungerechts, H., and Zensus, J. A.

Subjects
galaxie [X-rays], Photon, PARTICLE-ACCELERATION, ELECTRON ACCELERATION, BACKGROUND-RADIATION, Astrophysics, Electron, Nonthermal, BL Lacertae objects: individual (Markarian 421), galaxies: active, gamma rays: general, radiation mechanisms: nonthermal, X-rays: galaxies, 01 natural sciences, individual: Markarian 421 [BL Lacertae objects], LARGE-AREA TELESCOPE, individual (Markarian 421) [BL Lacertae objects], law.invention, Raigs gamma, law, MAGNETIC RECONNECTION, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Large area telescope, TEV BLAZARS, gamma, rays: general, ACTIVE GALACTIC NUCLEI, BL LACERTAE OBJECTS, LAC OBJECTS, CORRELATED VARIABILITY, Synchrotron, galaxies [X-rays], Spectral energy distribution, Degree of polarization, Electrónica, Física nuclear, Raigs X, Electricidad, Astrophysics - High Energy Astrophysical Phenomena, BL Lac object, Astronomy and Astrophysics, Space and Planetary Science, active [Galaxies], Astrophysics::High Energy Astrophysical Phenomena, Particle acceleration, general [Gamma rays], FOS: Physical sciences, Photon energy, 0103 physical sciences, X-rays, Radiation mechanisms, BL Lacertae objects, individual, Markarian 421, galaxies, active, gamma rays, general, radiation mechanisms, nonthermal, 010308 nuclear & particles physics, Gamma rays, Astronomy and Astrophysic, nonthermal [Radiation mechanisms], Light curve, Galaxies, Galàxies, Background radiation, ddc:520
Abstract

The astrophysical journal 819(2), 156 (2016). doi:10.3847/0004-637X/819/2/156, We present coordinated multiwavelength observations of the bright, nearby BL Lacertae object Mrk 421 taken in 2013 January–March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from radio to very high energy (VHE) γ-ray bands. NuSTAR yielded previously unattainable sensitivity in the 3–79 keV range, revealing that the spectrum softens when the source is dimmer until the X-ray spectral shape saturates into a steep ${\rm{\Gamma }}\approx 3$ power law, with no evidence for an exponential cutoff or additional hard components up to ~80 keV. For the first time, we observed both the synchrotron and the inverse-Compton peaks of the spectral energy distribution (SED) simultaneously shifted to frequencies below the typical quiescent state by an order of magnitude. The fractional variability as a function of photon energy shows a double-bump structure that relates to the two bumps of the broadband SED. In each bump, the variability increases with energy, which, in the framework of the synchrotron self-Compton model, implies that the electrons with higher energies are more variable. The measured multi band variability, the significant X-ray-to-VHE correlation down to some of the lowest fluxes ever observed in both bands, the lack of correlation between optical/UV and X-ray flux, the low degree of polarization and its significant (random) variations, the short estimated electron cooling time, and the significantly longer variability timescale observed in the NuSTAR light curves point toward in situ electron acceleration and suggest that there are multiple compact regions contributing to the broadband emission of Mrk 421 during low-activity states., Published by Univ.11032, Chicago, Ill. [u.a.]

Published
2016

39. Extreme HBL behavior of Markarian 501 during 2012

Author

Ahnen, M. L., Ansoldi, S., Bednarek, W., Paredes, J. M., Pedaletti, Giovanna, Peresano, M., Perri, L., Persic$, Prada Moroni, P. G., Prandini, E., Puljak, I., Garcia, J. R., Reichardt, I., Bernardini, E., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Satalecka, K., Schroeder, S., Schweizer, T., Shore, S. N., Sitarek, J., Berti, A., Šnidarić, I., Sobczynska, D., Stamerra, A., Strzys, M., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Bhattacharyya, W., Torres-Albà, N., Treves, A., Tsujimoto, S., Vanzo, G., Vazquez Acosta, M., Vovk, I., Ward, J. E., Will, M., Zarić, D., Arbet-Engels, A., Blanch, O., Baack, D., Balbo, M., Biland, A., Blank, M., Bretz, T., Bruegge, K., Bulinski, M., Buss, J., Dmytriiev, A., Dorner, D., Bonnoli, G., Einecke, S., Elsaesser, D., Herbst, T., Hildebrand, D., Kortmann, L., Linhoff, L., Mahlke, M., Mannheim, K., Mueller, S. A., Neise, D., Carosi, R., Neronov, A., Noethe, M., Oberkirch, J., Paravac, A., Rhode, W., Schleicher, B., Schulz, F., Sedlaczek, K., Shukla, A., Sliusar, V., Carosi, A., Walter, R., Archer, A., Benbow, W., Bird, R., Brose, R., Buckley, J. H., Bugaev, V., Christiansen, J. L., Cui, W., Daniel, M. K., Chatterjee, A., Falcone, A., Feng, Q., Finley, J. P., Gillanders, G. H., Gueta, O., Hanna, D., Hervet, O., Holder, J., Hughes, G., Huetten, Moritz, Colak, S. M., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, Maria, Krennrich, F., Kumar, S., Antonelli, L. A., Colin, P., Lang, M. J., Lin, T. T. Y., Maier, Gernot, McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Colombo, E., Petrashyk, A., Pichel, A., Pohl, Martin, Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Contreras, J. L., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Cortina, J., Wilhel, A., Williams, D. A., J Williamson, T., Zitzer, B., Perri, M., Verrecchia, F., Leto, C., Villata, M., Raiteri, C. M., Larionov, V. M., Covino, S., Blinov, D. A., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Nikiforova, A. A., Morozova, D. A., Troitskaya, Yu. V., Troitsky, I. S., Kurtanidze, O. M., Nikolashvili, M. G., Cumani, P., Kurtanidze, S. O., Kimeridze, G. N., Chigladze, R. A., Strigachev, A., Sadun, A. C., Moody, J. W., Chen, W. P., Lin, H. C., Acosta-Pulido, J. A., Arévalo, M. J., Da Vela, P., Carnerero, M. I., González-Morales, P. A., Manilla-Robles, A., Jermak, H., Steele, I., Mundel, C., Benítez, E., Hiriart, D., Smith, P. S., Max-Moerbeck, W., Dazzi, F., Readhead, A. C. S., Richards, J. L., Hovatta, T., Lähteenmäki, A., Tornikoski, M., Tammi, J., Georganopoulos, M., Baring, M. G., MAGIC Collaboration, FACT Collaboration, De Angelis, A., VERITAS Collaboration, De Lotto, B., Arcaro, C., Delfino, M., Delgado, J., Di Pierro, F., Doert, M., Domínguez, A., Dominis Prester, D., Doro, M., Eisenacher Glawion, D., Engelkemeier, M., Fallah Ramazani, V., Babić, A., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., García López, R. J., Garczarczyk, M., Gaug, M., Giammaria, P., Banerjee, B., Godinović, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Bangale, P., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Kuveždić, D., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., Barres de Almeida, U., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Barrio, J. A., Minev, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Becerra González, J., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Universitat de Barcelona, Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Babić, A., Banerjee, B., Bangale, P., Barresde Almeida, U., Barrio, J. A., Becerragonzález, J., Bednarek, W., Bernardini, E., Berti, A., Bhattacharyya, W., Blanch, O., Bonnoli, G., Carosi, R., Carosi, A., Chatterjee, A., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Cumani, P., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Ierro, F., Doert, M., Domínguez, A., Dominis Prester, D., Doro, M., Eisenacher Lawion, D., Engelkemeier, M., Fallah Ramazani, V., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., García López, R. J., Garczarczyk, M., Gaug, M., Giammaria, P., Godinović, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Kuve Dić, D., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Minev, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peresano, M., Perri, L., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Garcia, J. R., Reichardt, I., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Satalecka, K., Schroeder, S., Schweizer, T., Shore, S. N., Sitarek, J., Šnidarić, I., Sobczynska, D., Stamerra, A., Strzys, M., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Treves, A., Tsujimoto, S., Vanzo, G., Vazquez Acosta, M., Vovk, I., Ward, J. E., Will, M., Zarić, D., Arbet-Engels, A., Baack, D., Balbo, M., Biland, A., Blank, M., Bretz, T., Bruegge, K., Bulinski, M., Buss, J., Dmytriiev, A., Dorner, D., Einecke, S., Elsaesser, D., Herbst, T., Hildebrand, D., Kortmann, L., Linhoff, L., Mahlke, M., Mannheim, K., Mueller, S. A., Neise, D., Neronov, A., Noethe, M., Oberkirch, J., Paravac, A., Rhode, W., Schleicher, B., Schulz, F., Sedlaczek, K., Shukla, A., Sliusar, V., Walter, R., Archer, A., Benbow, W., Bird, R., Brose, R., Buckley, J. H., Bugaev, V., Christiansen, J. L., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Gillanders, G. H., Gueta, O., Hanna, D., Hervet, O., Holder, J., Hughes, G., Hütten, M., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., Maier, G., Mcarthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhel, A., Williams, D. A., J Williamson, T., Zitzer, B., Perri, M., Verrecchia, F., Leto, C., Villata, M., Raiteri, C. M., Jorstad, S. G., Larionov, V. M., Blinov, D. A., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Nikiforova, A. A., Morozova, D. A., Troitskaya, Yu. V., Troitsky, I. S., Kurtanidze, O. M., Nikolashvili, M. G., Kurtanidze, S. O., Kimeridze, G. N., Chigladze, R. A., Strigachev, A., Sadun, A. C., Moody, J. W., Chen, W. P., Lin, H. C., Acosta-Pulido, J. A., Arévalo, M. J., Carnerero, M. I., González-Morales, P. A., Manilla-Robles, A., Jermak, H., Steele, I., Mundell, C., Benítez, E., Hiriart, D., Smith, P. S., Max-Moerbeck, W., Readhead, A. C. S., Richards, J. L., Hovatta, T., Lähteenmäki, A., Tornikoski, M., Tammi, J., Georganopoulos, M., Baring, M. G., Swiss Federal Institute of Technology Zurich, University of Udine, Osservatorio Astronomicodi Roma, University of Padova, University of Rijeka, Saha Institute of Nuclear Physics, Max-Planck-Institut fur Physik (Werner-Heisenberg-Institut) Munchen, Complutense University, Instituto Astrofisico de Canarias, University of Lódz, Deutsches Elektronensynchroton DESY, Deutsches Elektronen-Synchrotron, Barcelona Institute of Science and Technology, University of Siena, University of La Laguna, Università di Padova and INFN, Technische Universität Dortmund, University of Würzburg, University of Turku, Autonomous University of Barcelona, University of Barcelona, University of Tokyo, Universitat Autonoma de Barcelona, Bulgarian Academy of Sciences, and Metsähovi Radio Observatory

Subjects
Astrofísica, Acceleration of particles, Radiation mechanisms: non-thermal, VHE [gamma ray], astroparticle physics, acceleration of particles, radiation mechanisms: non-thermal, BL Lacertae objects: general, BL Lacertae objects: individual: Mrk501, Astrophysics, 01 natural sciences, Spectral line, law.invention, law, Gamma ray astronomy, flux [gamma ray], individual: Mrk501 [BL Lacertae objects], MAGIC (telescope), 010303 astronomy & astrophysics, QC, QB, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Astronomy and Astrophysics, Space and Planetary Science, BL Lacertae objects: individual: Markarian 501, Methods: data analysis, Methods: observational, Polarization, Acceleration of particle, Synchrotron, VERITAS, Física nuclear, Compton scattering, Astrophysics - High Energy Astrophysical Phenomena, density [energy], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astroparticle physic, blazar, 0103 physical sciences, synchrotron, Astronomia de raigs gamma, Blazar, energy [electron], Cherenkov radiation, emission [energy], non-thermal [Radiation mechanisms], 010308 nuclear & particles physics, general [BL Lacertae objects], energy spectrum [X-ray], Institut für Physik und Astronomie, Spectral component, Astronomy and Astrophysic, Galaxies, MAGIC, Galàxies, Astronomía, Crab Nebula, Cherenkov counter, injection, 115 Astronomy and space science, correlation, fractional, ddc:520, spectral, Fermi Gamma-ray Space Telescope
Abstract

A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of $\sim$0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was $\sim$3 CU, and the peak of the high-energy spectral component was found to be at $\sim$2 TeV. This study reports very hard X-ray spectra, and the hardest VHE spectra measured to date for Mrk 501. The fractional variability was found to increase with energy, with the highest variability occurring at VHE, and a significant correlation between the X-ray and VHE bands. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency- peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The one-zone synchrotron self-Compton (SSC) scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behaviour seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays., Comment: 25 pages, 9 figures, accepted for publication in A&A. Corresponding authors: Gareth Hughes (gareth.hughes@cfa.harvard.edu), David Paneque (dpaneque@mppmu.mpg.de), Amit Shukla (amit.shukla@astro.uni-wuerzburg.de)

40. Insights into the High-energy γ-ray Emission of Markarian 501 from Extensive Multifrequency Observations in the Fermi Era

Author

Abdo, A. A., Ackermann, M., Ajello, M., Allafort, A., Baldini, Luca, Ballet, J., Barbiellini, G., Baring, M. G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bouvier, A., Brandt, T. J., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Cannon, A., Caraveo, P. A., Carrigan, S., Casandjian, J. M., Cavazzuti, E., Cecchi, C., Celik, O. ., Charles, E., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cohen Tanugi, J., Conrad, J., Cutini, S., Dermer, C. D., de Palma, F., do Couto, e. Silva E., Drell, P. S., Dubois, R., Dumora, D., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Fortin, P., Frailis, M., Fuhrmann, L., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I. A., Guillemot, L., Guiriec, S., Hayashida, M., Hays, E., Horan, D., Hughes, R. E., Johannesson, G., Johnson, A. S., Johnson, W. N., Kadler, M., Kamae, T., Katagiri, H., Kataoka, J., Knoedlseder, J., Kuss, M., Lande, J., Latronico, L., Lee, S. H., Lemoine Goumard, M., Longo, F., Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Madejski, G. M., Makeev, A., Max Moerbeck, W., Mazziotta, M. N., Mcenery, J. E., Mehault, J., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Naumann Godo, M., Nishino, S., Nolan, P. L., Norris, J. P., Nuss, E., Ohsugi, T., Okumura, A., Omodei, N., Orlando, E., Ormes, J. F., Paneque, D., Panetta, J. H., Parent, D., Pavlidou, V., Pearson, T. J., Pelassa, V., Pepe, M., Pesce Rollins, M., Piron, F., Porter, T. A., Raino, S., Rando, R., Razzano, Massimiliano, Readhead, A., Reimer, A., Reimer, O., Richards, J. L., Ripken, J., Ritz, S., Roth, M., Sadrozinski, H. F. W., Sanchez, D., Sander, A., Scargle, J. D., Sgro, C., Siskind, E. J., Smith, P. D., Spandre, G., Spinelli, P., Stawarz, L., Stevenson, M., Strickman, M. S., Sokolovsky, K. V., Suson, D. J., Takahashi, H., Takahashi, T., Tanaka, T., Thayer, J. B., Thayer, J. G., Thompson, D. J., Tibaldo, L., Torres, F., Tosti, G., Tramacere, A., Uchiyama, Y., Usher, T. L., Vandenbroucke, J., Vasileiou, V., Vilchez, N., Vitale, V., Waite, A. P., Wang, P., Wehrle, A. E., Winer, B. L., Wood, K. S., Yang, Z., Ylinen, T., Zensus, J. A., Ziegler, M., Aleksic, J., Antonelli, L. A., Antoranz, P., Backes, M., Barrio, J. A., Becerra, Gonzalez J., Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Bordas, P., Borla, Tridon D., Bosch Ramon, V., Bose, D., Braun, I., Bretz, T., Camara, M., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Dazzi, F., de Angelis, A., De Cea, del Pozo E., De Lotto, B., De Maria, M., De Sabata, F., Delgado, Mendez C., Diago, Ortega A., Doert, M., Dominguez, A., Dominis, Prester D., Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Garcia, Lopen R. J., Garczarczyk, M., Gaug, M., Giavitto, G., Godinovi, N., Hadasch, D., Herrero, A., Hildebrand, D., Hoehne Moench, D., Hose, J., Hrupec, D., Jogler, T., Klepser, S., Kraehenbuehl, T., Kranich, D., Krause, J., La Barbera, A., Leonardo, E., Lindfors, E., Lombardi, S., Lopez, M., Lorenz, E., Majumdar, P., Makariev, E., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldon, J., Moralejo, A., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paoletti, R., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Pegna, R. G., Perez Torres, M. A., Persic, M., Peruzzo, J., Pochon, J., PRADA MORONI, PIER GIORGIO, Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, T., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Rissi, M., Ruegamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Sanchez Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, STEVEN NEIL, Sierpowska Bartosik, A., Sillanpaa, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Storz, J., Strah, N., Struebig, J. C., Suric, T., Takalo, L. O., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Vankov, H., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Acciari, V. A., Arlen, T., Aune, T., Benbow, W., Boltuch, D., Bradbury, S. M., Buckley, J. H., Bugaev, V., Cesarini, A., Ciupik, L., Cui, W., Dickherber, R., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huang, D., Hui, C. M., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., Maier, G., Mcarthur, S., Mccann, A., Mccutcheon, M., Moriarty, P., Mukherjee, R., Ong, R., Otte, N., Pandel, D., Perkins, J. S., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Rovero, A. C., Schroedter, M., Sembroski, G. H., Senturk, G. D., Steele, D., Swordy, S. P., Tesic, G., Theiling, M., Thibadeau, S., Varlotta, A., Vincent, S., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wood, M., Zitzer, B., Villata, M., Raiteri, C. M., Aller, H. D., Aller, M. F., Arkharov, A. A., Blinov, D. A., Calcidese, P., Chen, W. P., Efimova, N. V., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Lahteenmaki, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Ligustri, R., Morozova, D. A., Nikolashvili, M. G., Sigua, L. A., Troitsky, I. S., Angelakis, E., Capalbi, M., Carraminana, A., Carrasco, L., Cassaro, P., de la Fuente, E., Gurwell, M. A., Kovalev, Y. Y., Kovalev, Y. u. A., Krichbaum, T. P., Krimm, H. A., Leto, P., Lister, M. L., Maccaferri, G., Moody, J. W., Mori, Y., Nestoras, I., Orlati, A., Pagani, C., Pace, C., Iii, Pearson R., Perri, M., Piner, B. G., Pushkarev, A. B., Ros, E., Sadun, A. C., Sakamoto, T., Tornikoski, M., Yatsu, Y., tschke V, Zook A., Raab, Fj, Rabeling, Ds, Racz, I, Radkins, H, Raffai, P, Rakhmanov, M, Ramet, Cr, Rankins, B, Rapagnani, P, Raymond, V, Re, V, Redwine, K, Reed, Cm, Reed, T, Regimbau, T, Reid, S, Reitze, Dh, Ricci, F, Riesen, R, Riles, K, Roberts, P, Robertson, Na, Robinet, F, Robinson, C, Robinson, El, Rocchi, A, Roddy, S, Rolland, L, Rollins, J, Romano, Jd, Romano, R, Romie, Jh, Rosinska, D, Rover, C, Rowan, S, Udiger, Ar, Ruggi, P, Ryan, K, Sakata, S, Sakosky, M, Salemi, F, Salit, M, Sammut, L, de la Jordana LS, Sandberg, V, Sannibale, V, Santamaria, L, Santiago Prieto, I, Santostasi, G, Saraf, S, Sassolas, B, Sathyaprakash, Bs, Sato, S, Satterthwaite, M, Saulson, Pr, Savage, R, Schilling, R, Schlamminger, S, Schnabel, R, Schofield, Rms, Schulz, B, Schutz, Bf, Schwinberg, P, Scott, J, Scott, Sm, Searle, Ac, Seifert, F, Sellers, D, Sengupta, As, Sentenac, D, Sergeev, A, Shaddock, Da, Shaltev, M, Shapiro, B, Shawhan, P, Weerathunga, Ts, Shoemaker, Dh, Sibley, A, Siemens, X, Sigg, D, Singer, A, Singer, L, Sintes, Am, Skelton, G, Slagmolen, Bjj, Slutsky, J, Smith, Jr, Smith, Mr, Smith, Nd, Smith, R, Somiya, K, Sorazu, B, Soto, J, Speirits, Fc, Sperandio, L, Stefszky, M, Stein, Aj, Steinlechner, J, Steinlechner, S, Steplewski, S, Stochino, A, Stone, R, Strain, Ka, Strigin, S, Stroeer, As, Sturani, R, Stuver, Al, Summerscales, Tz, Sung, M, Susmithan, S, Sutton, Pj, Swinkels, B, Szokoly, Gp, Tacca, M, Talukder, D, Tanner, Db, Tarabrin, Sp, Taylor, Jr, Taylor, R, Thomas, P, Thorne, Ka, Thorne, Ks, Thrane, E, Thuring, A, Titsler, C, Tokmakov, Kv, Toncelli, A, Tonelli, M, Torre, O, Torres, C, Torrie, Ci, Tournefier, E, Travasso, F, Traylor, G, Trias, M, Tseng, K, Turner, L, Ugolini, D, Urbanek, K, Vahlbruch, H, Vaishnav, B, Vajente, G, Vallisneri, M, van den Brand JFJ, Van Den Broeck, C, van der Putten, S, van der Sluys MV, van Veggel AA, Vass, S, Vasuth, M, Vaulin, R, Vavoulidis, M, Vecchio, A, Vedovato, G, Veitch, J, Veitch, Pj, Veltkamp, C, Verkindt, D, Vetrano, F, Vicere, A, Villar, Ae, Vinet, Jy, Vocca, H, Vorvick, C, Vyachanin, Sp, Waldman, Sj, Wallace, L, Wanner, A, Ward, Rl, Was, M, Wei, P, Weinert, M, Weinstein, Aj, Weiss, R, Wen, L, Wen, S, Wessels, P, West, M, Westphal, T, Wette, K, Whelan, Jt, Whitcomb, Se, White, D, Whiting, Bf, Wilkinson, C, Willems, Pa, Williams, Hr, Williams, L, Willke, B, Winkelmann, L, Winkler, W, Wipf, Cc, Wiseman, Ag, Woan, G, Wooley, R, Worden, J, Yablon, J, Yakushin, I, Yamamoto, H, Yamamoto, K, Yang, H, Yeaton Massey, D, Yoshida, S, Yu, P, Yvert, M, Zanolin, M, Zhang, L, Zhang, Z, Zhao, C, Zotov, N, Zucker, Me, Zweizig, J, Aptekar, Rl, Boynton, Wv, Briggs, Ms, Cline, Tl, Connaughton, V, Frederiks, Dd, Gehrels, N, Goldsten, Jo, Golovin, D, van der Horst AJ, Hurley, Kc, Kaneko, Y, von Kienlin, A, Kouveliotou, C, Krimm, Ha, Lin, L, Mitrofanov, I, Ohno, M, Pal'Shin, Vd, Rau, A, Sanin, A, Tashiro, Ms, Terada, Y, Yamaoka Kn, Y. A., Kus, V., Kuykendall, W., Kuze, M., Kuzhir, P., Kvasnicka, O., Kwee, R., La Rosa, A., La Rotonda, L., Labarga, L., Labbe, J., Lacasta, C., Lacava, F., Lacker, H., Lacour, D., Lacuesta, V. R., Ladygin, E., Lafaye, R., Laforge, B., Lagouri, T., Lai, S., Laisne, E., Lamanna, M., Lampen, C. L., Lampl, W., Lancon, E., Landgraf, U., Landon, M. P. J., Landsman, H., Lane, J. L., Lange, C., Lankford, A. J., Lanni, F., Lantzsch, K., Lapin, V. V., Laplace, S., Lapoire, C., Laporte, J. F., Lari, T., Larionov, A. V., Larner, A., Lasseur, C., Lassnig, M., Lau, W., Laurelli, P., Lavorato, A., Lavrijsen, W., Laycock, P., Lazarev, A. B., Lazzaro, A., Le Dortz, O., Le Guirriec, E., Le Maner, C., Le Menedeu, E., Leahu, M., Lebedev, A., Lebel, C., Lecompte, T., Ledroit Guillon, F., Lee, H., Lee, J. S. H., Lee, S. C., Lee, L., Lefebvre, M., Legendre, M., Leger, A., Legeyt, B. C., Legger, F., Leggett, C., Lehmacher, M., Lehmann, Miotto G., Lei, X., Leite, M. A. L., Leitner, R., Lellouch, D., Lellouch, J., Leltchouk, M., Lendermann, V., Leney, K. J. C., Lenz, T., Lenzen, G., Lenzi, B., Leonhardt, K., Leontsinis, S., Leroy, C., Lessard, J. R., Lesser, J., Lester, C. G., Leung Fook, Cheong A., Leveque, J., Levin, D., Levinson, L. J., Levitski, M. S., Lewandowska, M., Lewis, G. H., Leyton, M., Li, B., Li, H., Li, S., Li, X., Liang, Z., Liberti, B., Lichard, P., Lichtnecker, M., Lie, K., Liebig, W., Lifshitz, R., Lilley, J. N., Limosani, A., Limper, M., Lin, S. C., Linde, F., Linnemann, J. T., Lipeles, E., Lipinsky, L., Lipniacka, A., Liss, T. M., Lissauer, D., Lister, A., Litke, A. M., Liu, C., Liu, D., Liu, H., Liu, J. B., Liu, M., Liu, S., Liu, Y., Livan, M., Livermore, S. S. A., Lleres, A., Lloyd, S. L., Lobodzinska, E., Loch, P., Lockman, W. S., Lockwitz, S., Loddenkoetter, T., Loebinger, F. K., Loginov, A., Loh, C. W., Lohse, T., Lohwasser, K., Lokajicek, M., Loken, J., Lombardo, V. P., Long, R. E., Lopes, L., Lopez, Mateos D., Losada, M., Loscutoff, P., Lo Sterzo, F., Losty, M. J., Lou, X., Lounis, A., Loureiro, K. F., Love, J., Love, P. A., Lowe, A. J., Lu, F., Lu, J., Lu, L., Lubatti, H. J., Luci, C., Lucotte, A., Ludwig, A., Ludwig, D., Ludwig, I., Ludwig, J., Luehring, F., Luijckx, G., Lumb, D., Luminari, L., Lund, E., Lund Jensen, B., Lundberg, B., Lundberg, J., Lundquist, J., Lungwitz, M., Lupi, A., Lutz, G., Lynn, D., Lys, J., Lytken, E., Ma, H., L. L., Ma, Macana, Goia J. A., Maccarrone, G., Macchiolo, A., Macek, B., Machado Miguens, J., Macina, D., Mackeprang, R., Madaras, R. J., Mader, W. F., Maenner, R., Maeno, T., Maettig, P., Maettig, S., Magalhaes Martins, P. J., Magnoni, L., Magradze, E., Magrath, C. A., Mahalalel, Y., Mahboubi, K., Mahout, G., Maiani, C., Maidantchik, C., Maio, A., Majewski, S., Makida, Y., Makovec, N., Mal, P., Malecki, Pa, Malecki, P., Maleev, V. P., Malek, F., Mallik, U., Malon, D., Maltezos, S., Malyshev, V., Malyukov, S., Mameghani, R., Mamuzic, J., Manabe, A., Mandelli, L., Mandic, I., Mandrysch, R., Maneira, J., Mangeard, P. S., Manjavidze, I. D., Mann, A., Manning, P. M., Manousakis Katsikakis, A., Mansoulie, B., Manz, A., Mapelli, A., Mapelli, L., March, L., Marchand, J. F., Marchese, F., Marchesotti, M., Marchiori, G., Marcisovsky, M., Marin, A., Marino, C. P., Marroquim, F., Marshall, R., Marshall, Z., Martens, F. K., Marti Garcia, S., Martin, A. J., Martin, B., Martin, F. F., Martin, J. P., Martin, Ph, Universitat de Barcelona, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Théorique et Astroparticules (LPTA), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Fermi-LAT, Abdo, A. A., Ackermann, M., Ajello, M., Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., Baring, M. G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bouvier, A., Brandt, T. J., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Cannon, A., Caraveo, P. A., Carrigan, S., Casandjian, J. M., Cavazzuti, E., Cecchi, C., Çelik, Ö., Charles, E., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cohen Tanugi, J., Conrad, J., Cutini, S., Dermer, C. D., de Palma, F., Silva, E. do Couto e., Drell, P. S., Dubois, R., Dumora, D., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Fortin, P., Frailis, M., Fuhrmann, L., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I. A., Guillemot, L., Guiriec, S., Hayashida, M., Hays, E., Horan, D., Hughes, R. E., Jóhannesson, G., Johnson, A. S., Johnson, W. N., Kadler, M., Kamae, T., Katagiri, H., Kataoka, J., Knödlseder, J., Kuss, M., Lande, J., Latronico, L., Lee, S. H., Lemoine Goumard, M., Longo, Francesco, Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Madejski, G. M., Makeev, A., Max Moerbeck, W., Mazziotta, M. N., Mcenery, J. E., Mehault, J., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Naumann Godo, M., Nishino, S., Nolan, P. L., Norris, J. P., Nuss, E., Ohsugi, T., Okumura, A., Omodei, N., Orlando, E., Ormes, J. F., Paneque, D., Panetta, J. H., Parent, D., Pavlidou, V., Pearson, T. J., Pelassa, V., Pepe, M., Pesce Rollins, M., Piron, F., Porter, T. A., Rainò, S., Rando, R., Razzano, M., Readhead, A., Reimer, A., Reimer, O., Richards, J. L., Ripken, J., Ritz, S., Roth, M., Sadrozinski, H. F. W., Sanchez, D., Sander, A., Scargle, J. D., Sgrò, C., Siskind, E. J., Smith, P. D., Spandre, G., Spinelli, P., Stawarz, Ł., Stevenson, M., Strickman, M. S., Sokolovsky, K. V., Suson, D. J., Takahashi, H., Takahashi, T., Tanaka, T., Thayer, J. B., Thayer, J. G., Thompson, D. J., Tibaldo, L., Torres, D. F., Tosti, G., Tramacere, A., Uchiyama, Y., Usher, T. L., Vandenbroucke, J., Vasileiou, V., Vilchez, N., Vitale, V., Waite, A. P., Wang, P., Wehrle, A. E., Winer, B. L., Wood, K. S., Yang, Z., Ylinen, T., Zensus, J. A., Ziegler, M., Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Barrio, J. A., Becerra González, J., Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Bordas, P., Borla Tridon, D., Bosch Ramon, V., Bose, D., Braun, I., Bretz, T., Camara, M., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Dazzi, F., de Angelis, A., De Cea del Pozo, E., De Lotto, B., De Maria, M., De Sabata, F., Delgado Mendez, C., Diago Ortega, A., Doert, M., Domínguez, A., Dominis Prester, D., Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., García López, R. J., Garczarczyk, M., Gaug, M., Giavitto, G., Godinovi, N., Hadasch, D., Herrero, A., Hildebrand, D., Höhne Mönch, D., Hose, J., Hrupec, D., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., Krause, J., La Barbera, A., Leonardo, E., Lindfors, E., Lombardi, S., López, M., Lorenz, E., Majumdar, P., Makariev, E., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Nieto, D., Nilsson, K., Orito, R., Oya, I., Paoletti, R., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Pegna, R. G., Perez Torres, M. A., Persic, M., Peruzzo, J., Pochon, J., Prada Moroni, P. G., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, T., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Sánchez Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Storz, J., Strah, N., Struebig, J. C., Suric, T., Takalo, L. O., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Vankov, H., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Acciari, V. A., Arlen, T., Aune, T., Benbow, W., Boltuch, D., Bradbury, S. M., Buckley, J. H., Bugaev, V., Cesarini, A., Ciupik, L., Cui, W., Dickherber, R., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huang, D., Hui, C. M., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., Maier, G., Mcarthur, S., Mccann, A., Mccutcheon, M., Moriarty, P., Mukherjee, R., Ong, R., Otte, A. N., Pandel, D., Perkins, J. S., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Rovero, A. C., Schroedter, M., Sembroski, G. H., Senturk, G. D., Steele, D., Swordy, S. P., Tešić, G., Theiling, M., Thibadeau, S., Varlotta, A., Vincent, S., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wood, M., Zitzer, B., Villata, M., Raiteri, C. M., Aller, H. D., Aller, M. F., Arkharov, A. A., Blinov, D. A., Calcidese, P., Chen, W. P., Efimova, N. V., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Ligustri, R., Morozova, D. A., Nikolashvili, M. G., Sigua, L. A., Troitsky, I. S., Angelakis, E., Capalbi, M., Carramiñana, A., Carrasco, L., Cassaro, P., de la Fuente, E., Gurwell, M. A., Kovalev, Y. Y., Kovalev, Y. u. A., Krichbaum, T. P., Krimm, H. A., Leto, P., Lister, M. L., Maccaferri, G., Moody, J. W., Mori, Y., Nestoras, I., Orlati, A., Pagani, C., Pace, C., Pearson R., Iii, Perri, M., Piner, B. G., Pushkarev, A. B., Ros, E., Sadun, A. C., Sakamoto, T., Tornikoski, M., Yatsu, Y., Zook, A., Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
BL Lacertae objects: individual (Mrk 501), Photon, PARTICLE-ACCELERATION, Astrophysics, Electron, 01 natural sciences, CHERENKOV TELESCOPE SYSTEM, LARGE-AREA TELESCOPE, Raigs gamma, individual: Mrk 501 [BL Lacertae objects], EARLY-TYPE GALAXIES, 010303 astronomy & astrophysics, acceleration of particle, MAGNETOSONIC SHOCK-WAVES, acceleration of particles, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, TEV VARIABILITY, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Acceleradors de partícules, Gamma ray, individual (Mrk 501) [BL Lacertae objects], non-thermal [radiation mechanisms], BL LACERTAE OBJECTS, ACTIVE GALACTIC NUCLEI, LOG-PARABOLIC SPECTRA, X-RAY, active [galaxies], Eddington luminosity, BL Lacertae objects: individual: Mrk 501, symbols, Spectral energy distribution, Electrónica, Física nuclear, Electricidad, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, symbols.namesake, 0103 physical sciences, Blazar, 98.70.Rz, 98.54.Cm, 98.62.Py, BL Lacertae objects: general, gamma rays: general, radiation mechanisms: non-thermal, general [BL Lacertae objects], 010308 nuclear & particles physics, Gamma rays, Institut für Physik und Astronomie, Astronomy and Astrophysics, Galaxies, Particle accelerators, Galàxies, Space and Planetary Science, ddc:520, general [gamma rays], Fermi Gamma-ray Space Telescope
Abstract

著者人数：451名, Accepted: 2010-11-19, 資料番号: SA1002653000

41. Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

Author

Katsuaki Asano, I. Jiménez, A. Fuentes, C. M. Raiteri, D. Dominis Prester, E. Molina, E. Colombo, Y. V. Troitskaya, Nikola Godinovic, Sidika Merve Colak, Jenni Jormanainen, Yuki Iwamura, Alessandra Lamastra, Lab Saha, Antoniya Valcheva, Sunay Ibryamov, Elena G. Larionova, B. De Lotto, Evgeni Ovcharov, D. Zarić, Kazuma Ishio, David A. Green, M. Villata, D. Horan, Givi N. Kimeridze, Alexander Hahn, S. Nozaki, M. Perri, Michael D. Joner, D. Neise, S. Loporchio, R. J. García López, Marcello Giroletti, Victor A. Acciari, V. Fallah Ramazani, Tomohiko Oka, Daniela Dorner, Narek Sahakyan, J. Kushida, M. Kopp, Lorenzo Bellizzi, Noah Biederbeck, Joseph Moody, M. Gaug, L. Schneider, A. López-Oramas, Daniel Morcuende, N. Rizzi, Jose Luis Contreras, G. Vanzo, Rodolfo Carosi, L. Maraschi, Andrés Baquero, M. I. Carnerero, R. Iotov, Mosè Mariotti, A. Paravac, John Hoang, Ashwani Pandey, Z. R. Weaver, Francesco Longo, F. D'Ammando, S. Paiano, Elina Lindfors, Moritz Hütten, J. Herrera, Koji Noda, Abelardo Moralejo, Laura Eisenberger, E. Moretti, Julian Sitarek, Marcos López-Moya, Wlodek Bednarek, L. Di Venere, Ashot Chilingarian, U. Barres de Almeida, Elisa Bernardini, I. Agudo, M. Feige, R. Z. Ivanidze, O. A. Merkulova, D. Depaoli, M. Spencer, Massimo Persic, J. van Scherpenberg, Pratik Majumdar, L. Kunkel, K. Nishijima, Stefano Ansoldi, Juan Cortina, Kai Phillip Schmidt, A. Berti, Riccardo Paoletti, Saverio Lombardi, Daniel Mazin, M. V. Fonseca, Damir Lelas, R. J. C. Vera, Sanae Inoue, Giacomo D'Amico, Dominik Baack, C. Perennes, A. A. Nikiforova, Yating Chai, Stefan Cikota, G. M. Madejski, A. Arbet Engels, Daniel Kerszberg, Manuel Artero, E. Do Souto Espiñeira, Tomislav Terzić, J. Becerra González, Martin Makariev, R. Mirzoyan, Yoshiki Ohtani, G. A. Borman, Pawel Gliwny, Jose Miguel Miranda, A. De Angelis, Vitaly Neustroev, Wara Chamani, Oscar Blanch, T. S. Grishina, Martin Will, M. Vazquez Acosta, Nicola Giglietto, L. V. Larionova, Lea Heckmann, Francesco Gabriele Saturni, Jorge Otero-Santos, R. A. Chigladze, M. Balbo, N. Marchili, D. Hadasch, P. G. Prada Moroni, A. A. Vasilyev, M. G. Nikolashvili, Jordi Delgado, V. Ramakrishnan, Christian Fruck, G. Busetto, Victoria Moreno, Luca Tosti, A. Rugliancich, C. Nigro, Marina Manganaro, Valeri M. Larionov, M. Balokovic, Manuel Delfino, A. Strigachev, J. M. Paredes, Manash R. Samal, Stefano Covino, I. Vovk, H. C. Lin, Ž. Bošnjak, Stefano Menchiari, Rumen Bachev, Marc Ribó, Dorota Sobczyńska, Carolin Wunderlich, Bernd Schleicher, M. Minev, Antonio Stamerra, Maria-Isabel Bernardos, I. S. Troitskiy, Merja Tornikoski, E. N. Kopatskaya, Shunsuke Sakurai, Camilla Maggio, Chiara Righi, F. Verrecchia, P. Temnikov, S. G. Jorstad, T. Schweizer, Hidetoshi Kubo, Lluis Font, A. Y. Lien, Toshiaki Inada, A. Scherbantin, Lorand A. Sigua, G. Maneva, Stefano Truzzi, B. Machado de Oliveira Fraga, V. Bozhilov, M. Palatiello, Alessandro Marchini, Chaitanya Priyadarshi, Alessia Spolon, Léa Jouvin, Konstancja Satalecka, Tomoki Saito, Giovanni Ceribella, Michele Doro, S. O. Kurtanidze, Carlo Vigorito, Pablo Peñil, D. Strom, Giacomo Bonnoli, Adrian Biland, Ana Babić, Alicia Fattorini, D. Hildebrand, Satoshi Fukami, G. Ferrara, Y. Kajiwara, Matteo Cerruti, P. Da Vela, Vassil Verguilov, Lovro Pavletić, C. Delgado Mendez, Emilia Järvelä, S. Mićanović, Sergey S. Savchenko, Ivica Puljak, M. Noethe, Simone Mender, Francesco Dazzi, V. Vitale, Manuela Mallamaci, Ivana Batković, F. Leone, M. I. Martínez, J. Rico, Alan P. Marscher, C. Lorey, S. Ventura, Tjark Miener, Anne Lähteenmäki, David Paneque, Masahiro Teshima, Jarred Gershon Green, Wrijupan Bhattacharyya, Kari Nilsson, R. Walter, M. Strzys, D. Reinhart, E. Zaharieva, Wen Ping Chen, Vitalii Sliusar, Jürgen Besenrieder, Francesco Giordano, Antonio Tutone, Thomas Bretz, J. Buss, Alok C. Gupta, Simona Righini, O. M. Kurtanidze, Ciro Bigongiari, O. Vince, D. Elsaesser, C. Leto, M. Garczarczyk, Sargis Gasparyan, J. Kania, Dario Hrupec, R. López-Coto, Wolfgang Rhode, I. Snidaric, D. A. Morozova, Vladimir A. Hagen-Thorn, Mitsunari Takahashi, J. A. Acosta-Pulido, E. Prandini, Marie Karjalainen, D. Miceli, Goran Damljanović, Evgeni Semkov, Alice Donini, L. A. Antonelli, J. A. Barrio, Y. Suda, D. Carosati, V. D'Elia, Fabrizio Tavecchio, A. C. Sadun, Tihomir Surić, C. Casadio, Karl Mannheim, Santiago Ubach, Y. Kobayashi, F. Di Pierro, European Commission, European Research Council, Ministerio de Ciencia e Innovación (España), Generalitat de Catalunya, Federal Ministry of Education and Research (Germany), German Research Foundation, Swiss National Science Foundation, Croatian Science Foundation, Ministry of Education, Science and Technological Development (Serbia), Bulgarian National Science Fund, National Aeronautics and Space Administration (US), Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Artero, M., Asano, K., Babi??, A., Baquero, A., Barres de Almeida, U., Barrio, J. A., Batkovi??, I., Becerra Gonz??lez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Blanch, O., Bo??njak, ??., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D???amico, G., D???elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Delgado Mendez, C., Depaoli, D., Di Pierro, F., Di Venere, L., Do Souto Espi??eira, E., Dominis Prester, D., Donini, A., Doro, M., Fallah Ramazani, V., Fattorini, A., Ferrara, G., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Garc??a L??pez, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinovi??, N., Green, J. G., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., H??tten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jim??nez, I., Jormanainen, J., Jouvin, L., Kajiwara, Y., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., L??pez-Coto, R., L??pez-Moya, M., L??pez-Oramas, A., Loporchio, S., Machado de Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Mart??nez, M., Mazin, D., Menchiari, S., Mender, S., Mi??anovi??, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavleti??, L., Pe??il, P., Perennes, C., Persic, M., Prada Moroni, P. G., Prandini, E., Priyadarshi, C., Puljak, I., Rib??, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schmidt, K., Schweizer, T., Sitarek, J., nidari??, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Suri??, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzi??, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Zari??, D., Baack, D., Balbo, M., Biederbeck, N., Biland, A., Bretz, T., Buss, J., Dorner, D., Eisenberger, L., Elsaesser, D., Hildebrand, D., Iotov, R., Mannheim, K., Neise, D., Noethe, M., Paravac, A., Rhode, W., Schleicher, B., Sliusar, V., Walter, R., D???ammando, F., Horan, D., Lien, A. Y., Balokovi??, M., Madejski, G. M., Perri, M., Verrecchia, F., Leto, C., L??hteenm??ki, A., Tornikoski, M., Ramakrishnan, V., J??rvel??, E., Vera, R. J. C., Chamani, W., Villata, M., Raiteri, C. M., Gupta, A. C., Pandey, A., Fuentes, A., Agudo, I., Casadio, C., Semkov, E., Ibryamov, S., Marchini, A., Bachev, R., Strigachev, A., Ovcharov, E., Bozhilov, V., Valcheva, A., Zaharieva, E., Damljanovic, G., Vince, O., Larionov, V. M., Borman, G. A., Grishina, T. S., Hagen-Thorn, V. A., Kopatskaya, E. N., Larionova, E. G., Larionova, L. V., Morozova, D. A., Nikiforova, A. A., Savchenko, S. S., Troitskiy, I. S., Troitskaya, Y. V., Vasilyev, A. A., Merkulova, O. A., Chen, W. P., Samal, M., Lin, H. C., Moody, J. W., Sadun, A. C., Jorstad, S. G., Marscher, A. P., Weaver, Z. R., Feige, M., Kania, J., Kopp, M., Kunkel, L., Reinhart, D., Scherbantin, A., Schneider, L., Lorey, C., Acosta-Pulido, J. A., Carnerero, M. I., Carosati, D., Kurtanidze, S. O., Kurtanidze, O. M., Nikolashvili, M. G., Chigladze, R. A., Ivanidze, R. Z., Kimeridze, G. N., Sigua, L. A., Joner, M. D., Spencer, M., Giroletti, M., Marchili, N., Righini, S., Rizzi, N., Bonnoli, G., Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), MAGIC, FACT, Department of Electronics and Nanoengineering, Aalto-yliopisto, and Aalto University

Subjects
electron, PARTICLE-ACCELERATION, ELECTRON ACCELERATION, Radiation mechanisms: non-thermal, RAY, VHE [gamma ray], galaxies: active, BL Lacertae objects: individual: Mrk 421, radiation mechanisms: non-thermal, Electron, Astrophysics, GeV, 01 natural sciences, 7. Clean energy, LARGE-AREA TELESCOPE, law.invention, OBSERVATIONS, law, ultraviolet, optical, MAGIC (telescope), correlation [flux], 010303 astronomy & astrophysics, X-ray: flux, model: leptonic, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), BL-LACERTAE, individual: Mrk 421 [BL Lacertae objects], flux [X-ray], Gamma ray, flux: correlation, Galaxies: active, non-thermal [radiation mechanisms], Synchrotron, SWIFT OBSERVATIONS, active [galaxies], Spectral energy distribution, Física nuclear, Astrophysics - High Energy Astrophysical Phenomena, Lorentz, Flare, LOG-PARABOLIC SPECTRA, ACTIVE GALACTIC NUCLEI, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, radiation, mechanisms: non-thermal, LIGHT CURVES, X-RAY, MULTIWAVELENGTH, GLAST, leptonic [model], blazar, 0103 physical sciences, TeV, Blazar, 010308 nuclear & particles physics, Astronomy and Astrophysics, MAGIC, gamma ray: VHE, Space and Planetary Science, ddc:520, spectral, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Fermi Gamma-ray Space Telescope
Abstract

Full list of authors: Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Artero, M.; Asano, K.; Babić, A.; Baquero, A.; Barres de Almeida, U.; Barrio, J. A.; Batković, I.; Becerra González, J.; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Bernardos, M.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Blanch, O.; Bošnjak, Ž.; Busetto, G.; Carosi, R.; Ceribella, G.; Cerruti, M.; Chai, Y.; Chilingarian, A.; Cikota, S.; Colak, S. M.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V.; da Vela, P.; Dazzi, F.; de Angelis, A.; de Lotto, B.; Delfino, M.; Delgado, J.; Delgado Mendez, C.; Depaoli, D.; di Pierro, F.; di Venere, L.; Do Souto Espiñeira, E.; Dominis Prester, D.; Donini, A.; Doro, M.; Fallah Ramazani, V.; Fattorini, A.; Ferrara, G.; Fonseca, M. V.; Font, L.; Fruck, C.; Fukami, S.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giglietto, N.; Giordano, F.; Gliwny, P.; Godinović, N.; Green, J. G.; Green, D.; Hadasch, D.; Hahn, A.; Heckmann, L.; Herrera, J.; Hoang, J.; Hrupec, D.; Hütten, M.; Inada, T.; Inoue, S.; Ishio, K.; Iwamura, Y.; Jiménez, I.; Jormanainen, J.; Jouvin, L.; Kajiwara, Y.; Karjalainen, M.; Kerszberg, D.; Kobayashi, Y.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López-Coto, R.; López-Moya, M.; López-Oramas, A.; Loporchio, S.; Machado de Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menchiari, S.; Mender, S.; Mićanović, S.; Miceli, D.; Miener, T.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Morcuende, D.; Moreno, V.; Moretti, E.; Neustroev, V.; Nigro, C.; Nilsson, K.; Nishijima, K.; Noda, K.; Nozaki, S.; Ohtani, Y.; Oka, T.; Otero-Santos, J.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pavletić, L.; Peñil, P.; Perennes, C.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Priyadarshi, C.; Puljak, I.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Saturni, F. G.; Schmidt, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Spolon, A.; Stamerra, A.; Strom, D.; Strzys, M.; Suda, Y.; Surić, T.; Takahashi, M.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Tosti, L.; Truzzi, S.; Tutone, A.; Ubach, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Ventura, S.; Verguilov, V.; Vigorito, C. F.; Vitale, V.; Vovk, I.; Will, M.; Wunderlich, C.; Zarić, D.; Baack, D.; Balbo, M.; Biederbeck, N.; Biland, A.; Bretz, T.; Buss, J.; Dorner, D.; Eisenberger, L.; Elsaesser, D.; Hildebrand, D.; Iotov, R.; Mannheim, K.; Neise, D.; Noethe, M.; Paravac, A.; Rhode, W.; Schleicher, B.; Sliusar, V.; Walter, R.; D'Ammando, F.; Horan, D.; Lien, A. Y.; Baloković, M.; Madejski, G. M.; Perri, M.; Verrecchia, F.; Leto, C.; Lähteenmäki, A.; Tornikoski, M.; Ramakrishnan, V.; Järvelä, E.; Vera, R. J. C.; Chamani, W.; Villata, M.; Raiteri, C. M.; Gupta, A. C.; Pandey, A.; Fuentes, A.; Agudo, I.; Casadio, C.; Semkov, E.; Ibryamov, S.; Marchini, A.; Bachev, R.; Strigachev, A.; Ovcharov, E.; Bozhilov, V.; Valcheva, A.; Zaharieva, E.; Damljanovic, G.; Vince, O.; Larionov, V. M.; Borman, G. A.; Grishina, T. S.; Hagen-Thorn, V. A.; Kopatskaya, E. N.; Larionova, E. G.; Larionova, L. V.; Morozova, D. A.; Nikiforova, A. A.; Savchenko, S. S.; Troitskiy, I. S.; Troitskaya, Y. V.; Vasilyev, A. A.; Merkulova, O. A.; Chen, W. P; Samal, M.; Lin, H. C.; Moody, J. W.; Sadun, A. C.; Jorstad, S. G.; Marscher, A. P.; Weaver, Z. R.; Feige, M.; Kania, J.; Kopp, M.; Kunkel, L.; Reinhart, D.; Scherbantin, A.; Schneider, L.; Lorey, C.; Acosta-Pulido, J. A.; Carnerero, M. I.; Carosati, D.; Kurtanidze, S. O.; Kurtanidze, O. M.; Nikolashvili, M. G.; Chigladze, R. A.; Ivanidze, R. Z.; Kimeridze, G. N.; Sigua, L. A.; Joner, M. D.; Spencer, M.; Giroletti, M.; Marchili, N.; Righini, S.; Rizzi, N.; Bonnoli, G.; MAGIC Collaboration; Fact Collaboration.-- This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Aims. We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations. Methods. The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsahovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. Results. The very-high-energy (VHE; E 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow dierent patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e., orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3. A VHE flare observed on MJD 57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario.We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from 0 min = 2104 to 0 max = 6105. © 2021 Georg Thieme Verlag. All rights reserved., The MAGIC Collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF, MPG and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovación (MICINN) (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-5-R, FPA2017-90566-REDC, PID2019-104114RB-C31, PID2019-104114RB-C32, PID2019-105510GB-C31,PID2019-107847RB-C41, PID2019-107847RB-C42, PID2019-107847RB-C44, PID2019-107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2016-0588, SEV-2017-0709 and CEX2019-000920-S, and “María de Maeztu” CEX2019-000918-M, the Unidad de Excelencia “María de Maeztu” MDM-2015-0509-18-2 and the “la Caixa” Foundation (fellowship LCF/BQ/PI18/11630012) and by the CERCA program of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02; by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3; the Polish National Research Centre grant UMO-2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq and FAPERJ. The important contributions from ETH Zurich grants ETH-10.08-2 and ETH-27.12-1 as well as the funding by the Swiss SNF and the German BMBF (Verbundforschung Astro- und Astroteilchenphysik) and HAP (Helmoltz Alliance for Astroparticle Physics) are gratefully acknowledged. Part of this work is supported by Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Center SFB 876 “Providing Information by Resource-Constrained Analysis”, project C3. We are thankful for the very valuable contributions from E. Lorenz, D. Renker and G. Viertel during the early phase of the project. We thank the Instituto de Astrofísica de Canarias for allowing us to operate the telescope at the Observatorio del Roque de los Muchachos in La Palma, the Max-Planck-Institut für Physik for providing us with the mount of the former HEGRA CT3 telescope, and the MAGIC collaboration for their support. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. This work performed in part under DOE Contract DE-AC02-76SF00515. This work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC; Italy) and the California Institute of Technology (USA). This research has also made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. A.A.E and D.P acknowledge support from the Deutsche Forschungs gemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC-2094 – 390783311. M. B. acknowledges support from the YCAA Prize Postdoctoral Fellowship and from the Black Hole Initiative at Harvard University, which is funded in part by the Gordon and Betty Moore Foundation (grant GBMF8273) and in part by the John Templeton Foundation. This publication makes use of data obtained at the Metsähovi Radio Observatory, operated by Aalto University in Finland. This research has made use of data from the OVRO 40-m monitoring program (Richards et al. 2011) which is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST-1109911. I.A. acknowledges financial support from the Spanish “Ministerio de Ciencia e Innovación” (MCINN) through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). Acquisition and reduction of the MAPCAT data was supported in part by MICINN through grants AYA2016-80889-P and PID2019-107847RB-C44. The MAPCAT observations were carried out at the German-Spanish Calar Alto Observatory, which is jointly operated by Junta de Andalucía and Consejo Superior de Investigaciones Científicas. C.C. acknowledges support from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program under the grant agreement No 771282. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants KP-06-H28/3 (2018), KP-06-H38/4 (2019) and KP-06-KITAJ/2 (2020). We acknowledge support by Bulgarian National Science Fund under grant DN18-10/2017 and National RI Roadmap Projects DO1-277/16.12.2019 and DO1-268/16.12.2019 of the Ministry of Education and Science of the Republic of Bulgaria. This research was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (contract No 451-03-68/2020-14/200002). G.D. acknowledges observing grant support from the Institute of Astronomy and Rozhen NAO BAS through the bilateral joint research project “Gaia Celestial Reference Frame (CRF) and fast variable astronomical objects” (2020–2022, head – G. Damljanovic). The BU group was supported in part by NASA Fermi guest investigator program grants 80NSSC19K1505 and 80NSSC20K1566. This study was based in part on observations conducted using the 1.8 m Perkins Telescope Observatory (PTO) in Arizona, which is owned and operated by Boston University. This article is partly based on observations made with the LCOGT Telescopes, one of whose nodes is located at the Observatorios de Canarias del IAC on the island of Tenerife in the Observatorio del Teide. This article is also based partly on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC. The Abastumani team acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR-19-6174. Based on observations with the Medicina telescope operated by INAF – Istituto di Radioastronomia.

Published
2021

42. Unraveling the Complex Behavior of Mrk 421 with Simultaneous X-Ray and VHE Observations during an Extreme Flaring Activity in 2013 April

Author

Simonetta Puccetti, D. Dominis Prester, M. Makariev, Alice Donini, Sofia O. Kurtanidze, G. Bonnoli, Julian Sitarek, D. Dorner, Yoshiki Ohtani, J. Becerra González, S. Ventura, S. Ansoldi, L. Nogués, J. Besenrieder, A. Rugliancich, P. Munar-Adrover, Jose Luis Contreras, B. Jordan, I. Puljak, Pawel Gliwny, L. V. Larionova, L. Di Venere, Sunay Ibryamov, Abelardo Moralejo, M. I. Martínez, B. De Lotto, Juan Cortina, A. A. Mokrushina, E. Moretti, Kaya Mori, Maria Petropoulou, Elena G. Larionova, J. Rico, Juan Abel Barrio, Narek Sahakyan, A. Fattorini, C. Fruck, F. Del Puppo, F. Verrecchia, Victoria Moreno, Chiara Righi, M. V. Fonseca, Elina Lindfors, Justin D. Finke, D. A. Morozova, V. D'Elia, A. López-Oramas, M. G. Nikolashvili, John Hoang, Susumu Inoue, L. Maraschi, R. Paoletti, R. Reinthal, A. Strigachev, Saverio Lombardi, T. Schweizer, E. Do Souto Espiñeira, Tomislav Terzić, Ferdinando Giordano, Fabrizio Tavecchio, C. Nigro, B. Banerjee, Bernd Schleicher, A. Hahn, R. G. Chanishvili, Francesco Longo, M. Will, Shunsuke Sakurai, Ll. Font, Takeshi Oka, Davide Depaoli, Alan P. Marscher, L. Saha, D. Elsaesser, Antonio Stamerra, R. Carosi, G. Ceribella, Joni Tammi, V. Fallah Ramazani, D. Lelas, T. Guever, M. Teshima, J. M. Paredes, Dorota Sobczyńska, Zeljka Bosnjak, Chakali Eswaraiah, A. C. R. Readhead, G. Busetto, Jorge Otero-Santos, Mislav Baloković, J. L. Richards, R. A. Chigladze, Y. Chai, J. Kushida, Seiya Nozaki, Kari Nilsson, U. Barres de Almeida, L. Foffano, Ciro Bigongiari, Saša Mićanović, V. Vitale, Wen Ping Chen, P. Temnikov, T. Saito, Andrei Berdyugin, David H. Green, D. Strom, F. Di Pierro, E. N. Kopatskaya, Stefano Covino, D. Miceli, S. Gasparyan, D. Blinov, G. Maneva, E. Molina, S. G. Jorstad, T. Surić, M. Mariotti, I. Šnidarić, Satoshi Fukami, H. Kubo, M. Vazquez Acosta, R. López-Coto, Kazuma Ishio, Y. Iwamura, M. Gaug, A. Lamastra, A. C. Sadun, J. Herrera, G. Vanzo, Oscar Blanch, T. S. Grishina, Walter Max-Moerbeck, Anne Lähteenmäki, S. M. Colak, Valeri M. Larionov, C. M. Raiteri, C. Maggio, O. M. Kurtanidze, S. Cikota, D. Ninci, G. Ferrara, A. De Angelis, Rumen Bachev, Yu. V. Troitskaya, M. Minev, Georgi Latev, Elisa Bernardini, Other groups, L. Pavletić, Elisa Prandini, Goran Damljanović, Evgeni Semkov, M. Delfino, Wolfgang Rhode, Yusuke Suda, Massimo Persic, Carlo Vigorito, A. Berti, Paul S. Smith, K. Noda, Dario Hrupec, C. Leto, Victor A. Acciari, K. Nishijima, B. Machado de Oliveira Fraga, Mitsunari Takahashi, P. Peñil, L. Bellizzi, Serena Loporchio, Jose Miguel Miranda, N. Godinović, M. Strzys, Ashot Chilingarian, N. Giglietto, U. Colin, W. Bednarek, Simone Mender, Moritz Hütten, W. Bhattacharyya, I. Agudo, R. Mirzoyan, Louis Antonelli, Dominik Baack, P. Majumdar, G. M. Madejski, A. Arbet Engels, Vitaly Neustroev, J. W. Moody, Luca Tosti, M. Villata, D. Morcuende, N. Torres-Albà, I. Vovk, Jordi Delgado, H. C. Lin, Kevin Schmidt, Talvikki Hovatta, D. Hadasch, M. Palatiello, Y. Kajiwara, Francesco Dazzi, M. Mallamaci, O. Vince, M. Peresano, Yosuke Kobayashi, P. Da Vela, F. D'Ammando, K. Mannheim, R. J. García López, Ivan S. Troitsky, Tjark Miener, David Paneque, A. Biland, Marina Manganaro, P. G. Prada Moroni, Merja Tornikoski, Matteo Cerruti, M. López, Konstancja Satalecka, D. Mazin, Michele Doro, J. Barnes, F. Leone, M. Ribó, J. van Scherpenberg, A. Babić, Alessia Spolon, Léa Jouvin, Manasvita Joshi, Vassil Verguilov, Daniel Kerszberg, V. Ramakrishnan, D. Zarić, Tomohiro Inada, E. Colombo, M. Perri, M. Garczarczyk, Federal Ministry of Education and Research (Germany), Istituto Nazionale di Astrofisica, Swiss National Science Foundation, Istituto Nazionale di Fisica Nucleare, Ministerio de Economía y Competitividad (España), European Commission, Department of Atomic Energy (India), Ministry of Education, Culture, Sports, Science and Technology (Japan), Japan Society for the Promotion of Science, Ministry of Education, Youth and Science (Bulgaria), Academy of Finland, Croatian Science Foundation, University of Rijeka, German Research Foundation, National Centre for Research and Development (Poland), Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, National Aeronautics and Space Administration (US), Department of Energy (US), Centre National de la Recherche Scientifique (France), Russian Science Foundation, Gordon and Betty Moore Foundation, John Templeton Foundation, Shota Rustaveli National Science Foundation, Comisión Nacional de Investigación Científica y Tecnológica (Chile), Metsähovi Radio Observatory, Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Magic, Collaboration, Other Groups And, Collaborator, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. A., Baack, D., Babic, A., Banerjee, B., De Almeida, U. B., Barrio, J. A., Gonzalez, J. B., Bednarek, W., Bellizzi, L. K., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bosnjak, Z., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Vela, P. D., Dazzi, F., Angelis, A. D., Lotto, B. D., Puppo, F. D., Delfino, M., Delgado, J., Depaoli, D., Pierro, F. D., Venere, L. D., Souto Espiñeira, E. D., Prester, D. D., Donini, A., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. F., Fattorini, A., Ferrara, G., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Lopez, R. J. G., Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinovic, N., Green, D., Hadasch, D., Hahn, A., Hassan, T., Herrera, J., Hoang, J., Hrupec, D., Hutten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jouvin, L., Kajiwara, Y., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Loporchio, S., De Oliveira Fraga, B. M., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Mender, S., Micanovic, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletic, L., Peñil, P., Peresano, M., Persic, M., Moroni, P. G. P., Prandini, E., Puljak, I., Rhode, W., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Suric, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Tosti, L., Scherpenberg, J. V., Vanzo, G., Acosta, M. V., Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Zaric, D., Petropoulou, M., Finke, J., D'Ammando, F., Balokovic, M., Madejski, G., Mori, K., Puccetti, S., Leto, C., Perri, M., Verrecchia, F., Villata, M., Raiteri, C. M., Agudo, I., Bachev, R., Berdyugin, A., Blinov, D. A., Chanishvili, R., Chen, W. P., Chigladze, R., Damljanovic, G., Eswaraiah, C., Grishina, T. S., Ibryamov, S., Jordan, B., Jorstad, S. G., Joshi, M., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Larionova, L. V., Larionov, V. M., Latev, G., Lin, H. C., Marscher, A. P., Mokrushina, A. A., Morozova, D. A., Nikolashvili, M. G., Semkov, E., Smith, P. S., Strigachev, A., Troitskaya, Y. V., Troitsky, I. S., Vince, O., Barnes, J., Guver, T., Moody, J. W., Sadun, A. C., Hovatta, T., Richards, J. L., Max-Moerbeck, W., Readhead, A. C. S., Lahteenmaki, A., Tornikoski, M., Tammi, J., Ramakrishnan, V., and Reinthal, R.

Subjects
Individual sources Mrk 421, Flux, Astrophysics, Blazar, 7. Clean energy, 01 natural sciences, Imaging Atmospheric Cherenkov observations, Gamma-ray, Active galaxie, Relativistic jet, MAGIC (telescope), BL lacertae objects, BL Lacertae objects, Blazars, Active galaxies, Markarian galaxies, Gamma-ray detectors, Gamma-rays, Relativistic jets, High energy astrophysics, Observational astronomy, 010303 astronomy & astrophysics, astro-ph.HE, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gamma ray, X-ray, Markarian galaxie, Física nuclear, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics and Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Individual sources Mrk 421, Imaging Atmospheric Cherenkov observations, MAGIC, BL Lacertae objects, Blazars, Active galaxies, Markarian galaxies, Gamma-ray detectors, Gamma-rays, Relativistic jets, High energy astrophysics, Observational astronomy, Plasmoid, Astrophysics::Cosmology and Extragalactic Astrophysics, BL Lacertae object, High energy astrophysic, 0103 physical sciences, Gamma-ray detector, 010308 nuclear & particles physics, Astronomy and Astrophysics, Magnetic reconnection, Light curve, MAGIC, 13. Climate action, Space and Planetary Science, ddc:520, High Energy Astrophysical Phenomena
Abstract

We report on a multiband variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 19. The study uses, among others, data from GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT), Swift, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Large Area Telescope, Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma Imaging Cherenkov (MAGIC). The large blazar activity and the 43 hr of simultaneous NuSTAR and MAGIC/VERITAS observations permitted variability studies on 15 minute time bins over three X-ray bands (3-7 keV, 7-30 keV, and 30-80 keV) and three very-high-energy (VHE; >0.1 TeV) gamma-ray bands (0.2-0.4 TeV, 0.4-0.8 TeV, and >0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all of the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-rays and the VHE gamma-rays. The three VHE bands and the three X-ray bands are positively correlated with no time lag, but the strength and characteristics of the correlation change substantially over time and across energy bands. Our findings favor multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux-flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer. © 2020. The American Astronomical Society. All rights reserved., The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-2-R, FPA2017-827 29-C6-6-R, FPA2017-82729-C6-5-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2017-87055-C2-2-P, and FPA 201790566REDC), the Indian Department of Atomic Energy, the Japanese JSPS and MEXT, the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO-1153/28.08.2018 and the Academy of Finland grant No. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia "Severo Ochoa" SEV-20160588 and SEV-2015-0548, and Unidad de Excelencia "Maria de Maeztu" MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382, and by the Brazilian MCTIC, CNPq and FAPERJ. The Fermi-LAT.Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat a l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucleaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K..A..Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Etudes Spatiales in France. This work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC; Italy) and the California Institute of Technology (USA). D.P. and A.B. are grateful to Amy Furniss and Wystan Benbow for providing the VERITAS VHE gamma-ray fluxes and for useful discussions about them. M.P. acknowledges support from the Lyman Jr. Spitzer Postdoctoral Fellowship and NASA Fermi grant No. 80NSSC18K1745., and J.F. is partially supported by NASA under contract S-15633Y. M.B. acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program (grant NNX14AQ07H) and the black hole Initiative at Harvard University, which is funded in part by the Gordon and Betty Moore Foundation (grant GBMF8273) and in part by the John Templeton Foundation. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 18-13/2017, DN 18-10/2017, KP06-H28/3 (2018), and KP-06-PN38/1 (2019), as well as for the Spanish MIMECO (AYA2016-80889-P, RYC-2013-14511) and the IAA-CSIC "Severo Ochoa" program SEV2017-0709. The St. Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. The Abastumani team acknowledges financial support of the project FR/638/6-320/12 by the Shota Rustaveli National Science Foundation under contract 31/77. T.G. acknowledges support from Istanbul University (Project numbers 49429 and 48285), Bilim Akademisi (BAGEP program), and TUBITAK (project numbers 13AT100-431, 13AT100-466, and 13AT60-430). The Boston University effort was supported in part by NASA grants NNX12AO90G and NNX14AQ58G. Data from the Steward Observatory spectropolarimetric monitoring project were used in this paper. This program is supported by Fermi Guest Investigator grants NNX08AW56G, NNX09 AU10G, NNX12AO93G, and NNX15AU81G. The OVRO 40 m monitoring program is supported in part by NASA grants NNX08AW31G and NNX11A043G and NSF grants AST-0808050 and AST-1109911. The Metsahovi team acknowledges the support from the Academy of Finland to our observing projects (numbers 212656, 210338, 121148, and others). W.M. acknowledges support from CONICYT project Basal AFB-170002.

Published
2020

43. Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009

Author

K. Nishijima, J. L. Richards, Stefano Covino, G. Piner, D. Dominis Prester, U. Menzel, A. Flinders, D. Tescaro, Louis Antonelli, D. Galindo, Aaron Dominguez, S. Schröder, Elena G. Larionova, Kari Nilsson, Paul S. Smith, A. McCann, T. S. Grishina, Wen Ping Chen, M. Will, Pratik Majumdar, J. E. Ward, Daniela Dorner, Dariusz Gora, P. Moriarty, C. Rulten, Soebur Razzaque, D. Garrido Terrats, K. Frantzen, Joseph Moody, Wystan Benbow, G. Hughes, K. Ragan, Ralph Bird, L. Perri, M. Gaug, T. Sakamoto, Valeri M. Larionov, Elina Lindfors, G. H. Sembroski, Daniel Mazin, Ievgen Vovk, A. Hahn, M. Hütten, N. H. Park, Alexander B. Pushkarev, G. Maccaferri, Thomas Bretz, P. Wilcox, P. Kar, D. Nakajima, R. Zanin, J. Herrera, Wei Cui, Amanda Weinstein, J. Palacio, P. G. Prada Moroni, Frank Krennrich, Matthew L. Lister, A. Berti, A. Cesarini, M. Kertzman, A. La Barbera, Walter Max-Moerbeck, E. Colombo, M. Villata, M. P. Connolly, Adrian Biland, D. S. Hanna, Ana Babić, D. Eisenacher Glawion, Juan Abel Barrio, John L. Quinn, M. Capalbi, Koji Noda, Arka Chatterjee, Elisa Bernardini, A. Sillanpää, Adrian Rovero, Antonio Stamerra, J. V. Tucci, M. Nievas Rosillo, M. Palatiello, L. V. Larionova, S. N. Shore, R. Mukherjee, M. J. Lang, Daniel Nieto, M. I. Martínez, S. Bonnefoy, J. Kushida, P. Giammaria, P. Bangale, Wolfgang Rhode, Gernot Maier, G. Pedaletti, L. O. Takalo, Margo F. Aller, Jose Luis Contreras, Andrei Berdyugin, J. A. Zensus, E. Roache, V. Verguilov, D. Fidalgo, C. Pace, Thomas P. Krichbaum, Francesco Dazzi, Juan Cortina, M. Engelkemeier, G. H. Gillanders, A. Carraminyana, S. P. Wakely, Mosè Mariotti, J. Rico, A. Fernández-Barral, R. Clavero, J. Becerra González, A.-K. Overkemping, S. O. Kurtanidze, Sabrina Einecke, Abraham D. Falcone, A. González Muñoz, Evgenia N. Kopatskaya, Lars Fuhrmann, Nikola Godinovic, Benito Marcote, Karlen Shahinyan, Takashi Saito, W. Bednarek, C. Schultz, Marcos Santander, Fabrizio Tavecchio, J. Rodriguez Garcia, E. Pueschel, Ll. Font, A. C. Sadun, A. Popkow, J. Grube, V. Bugaev, Anthony C. S. Readhead, R. Ligustri, A. Archer, I. Snidaric, Yusuke Konno, P. Calcidese, M. Strzys, A. Pichel, Saverio Lombardi, B. De Lotto, Markus Garczarczyk, N. Kelley-Hoskins, J. Tyler, Ann E. Wehrle, B. Banerjee, S. Buson, D. Hadasch, N. Otte, Maria G. Nikolashvili, Gordon T. Richards, L. Nogués, B. Biasuzzi, Juri Poutanen, U. Barres de Almeida, J. P. Finley, K. Mallot, S. Paiano, Marcello Giroletti, I. Nestoras, A. De Angelis, A. Treves, Vitaly Neustroev, X. Paredes-Fortuny, T. B. Humensky, R. A. Ong, Karl Mannheim, J. H. Buckley, Yu. A. Kovalev, R. J. García López, H. Fleischhack, G. N. Kimeridze, I. Sadeh, David A. Williams, Y. Mori, M. V. Fonseca, W. Idec, Matthias Kadler, Yuri Y. Kovalev, Stefano Ansoldi, Riccardo Paoletti, K. Kodani, J. P. Norris, O. M. Kurtanidze, N. V. Efimova, Y. Hanabata, Arkady A. Arkharov, Anne Lähteenmäki, Abelardo Moralejo, G. Maneva, Masahiro Teshima, A. C. Zook, Dario Hrupec, P. Antoranz, B. Zitzer, Hugh Dickinson, R. A. Chigladze, M. Peresano, Ekaterina Koptelova, S. Archambault, M. A. Lopez, T. Steinbring, P. Temnikov, P. Leto, Massimo Persic, J. M. Paredes, Hugh D. Aller, F. Borracci, S. O'Brien, T. Surić, I. Telezhinsky, I. Reichardt, Jamie Holder, G. Vanzo, R. Pearson, Julia Thaele, G. Bonnoli, Mark Gurwell, Eduardo Ros, Andrea Orlati, S. Griffin, L. A. Sigua, Diego F. Torres, Alessandro Carosi, Ruben Lopez-Coto, Maria Krause, Y. Yatsu, A. Wilhelm, Jose Miguel Miranda, Anushka Udara Abeysekara, T. Schweizer, P. Cassaro, Razmik Mirzoyan, E. Moretti, Damir Lelas, Francesco Longo, V. Fallah Ramazani, P. Kaaret, Dorota Sobczyńska, L. Maraschi, Kirill Sokolovsky, Tomislav Terzić, Lucy Fortson, E. de Ona Wilhelmi, Julian Sitarek, C. Fruck, T. Toyama, Ivica Puljak, Max Ludwig Ahnen, David Kieda, F. Di Pierro, Pierre Colin, M. Buchovecky, Oscar Blanch, P. Da Vela, A. Niedzwiecki, Emmanouil Angelakis, M. Doert, M. H. Wu, Ivan S. Troitsky, C. Pagani, David Paneque, Q. Feng, Vladimir A. Hagen-Thorn, E. De la Fuente, E. Prandini, C. M. Raiteri, L. Carrasco, D. Guberman, Jeremy S. Perkins, Martin Pohl, Marina Manganaro, H. A. Krimm, Merja Tornikoski, Konstancja Satalecka, Michele Doro, Dmitry A. Blinov, M. Perri, J. Hose, D. Elsaesser, Daria A. Morozova, P. T. Reynolds, M. Hayashida, Marc Ribó, Hidetoshi Kubo, M. Makariev, Swiss Federal Institute of Technology Zurich, University of Udine, INAF National Institute for Astrophysics, University of Siena, University of Rijeka, Saha Institute of Nuclear Physics, Max Planck Institute for Physics, Complutense University, University of La Laguna, University of Łódź, German Electron Synchrotron, Autonomous University of Barcelona, University of Würzburg, University of Padova, Institute of Space Studies of Catalonia, Dortmund University, Finnish MAGIC Consortium, University of Barcelona, The University of Tokyo, Bulgarian Academy of Sciences, Osservatorio Astronomicodi Roma, University of Pisa, ICREA, University of Maryland, College Park, McGill University, Washington University St. Louis, Harvard University, University College Dublin, University of California Los Angeles, National University of Ireland, Galway, Purdue University, Iowa State University, Pennsylvania State University, University of Utah, University of Minnesota Twin Cities, Adler Planetarium and Astronomy Museum, University of Delaware, Columbia University, University of Iowa, DePauw University, Georgia Institute of Technology, University of Chicago, NASA Goddard Space Flight Center, Universidad de Buenos Aires, Cork Institute of Technology, University of California Santa Cruz, Argonne National Laboratory, University of Johannesburg, University of Michigan, Ann Arbor, St. Petersburg State University, RAS - Pulkovo Astronomical Observatory, Circolo Astrofili Talmassons, Osservatorio Astrofisico della Regione Autonoma Valle d'Aosta, Georgian National Academy of Sciences, National Central University, Aoyama Gakuin University, University of Colorado Denver, Brigham Young University, Tokyo Institute of Technology, Instituto Nacional de Astrofisica Optica y Electronica, Universidad de Guadalajara, University of Denver, University of Arizona, Space Science Institute, Pomona College, University of Leicester, ASI Science Data Center, University of Trento, RAS - P.N. Lebedev Physics Institute, Max Planck Institute for Radio Astronomy, Whittier College, Metsähovi Radio Observatory, INAF Istituto di Radioastronomia, Osservatorio Astrofisico di Catania, California Institute of Technology, Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., Barres De Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Bernardini, E., Berti, Alessio, Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Buson, S., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., De Oña Wilhelmi, E., Di Pierro, F., Doert, M., Domã­nguez, A., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Eisenacher Glawion, D., Elsaesser, D., Engelkemeier, M., Fallah Ramazani, V., Fernández Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., García López, R. J., Garczarczyk, M., Garrido Terrats, D., Gaug, M., Giammaria, P., Godinoviä , N., González Muñoz, A., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, Francesco, Lã³pez, M., López Coto, R., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martã­nez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nilsson, K., Nishijima, K., Noda, K., Noguã©s, L., Overkemping, A., Paiano, S., Palacio, J., Palatiello, Michele, Paneque, D., Paoletti, R., Paredes, J. M., Paredes Fortuny, X., Pedaletti, G., Peresano, M., Perri, L., Persic, M., Poutanen, J., Prada Moroni, P. G., Prandini, E., Puljak, I., Reichardt, I., Rhode, W., Ribã³, M., Rico, J., Rodriguez Garcia, J., Saito, T., Satalecka, K., Schrã¶der, S., Schultz, C., Schweizer, T., Shore, S. N., Sillanpã¤ã¤, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Suriä , T., Takalo, L., Tavecchio, F., Temnikov, P., Terziä , T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Vanzo, G., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Abeysekara, A. U., Archambault, S., Archer, A., Benbow, W., Bird, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Connolly, M. P., Cui, W., Dickinson, H. J., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Flinders, A., Fortson, L., Gillanders, G. H., Griffin, S., Grube, J., Hã¼tten, M., Hanna, D., Holder, J., Humensky, T. B., Kaaret, P., Kar, P., Kelley Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Maier, G., Mccann, A., Moriarty, P., Mukherjee, R., Nieto, D., O'Brien, S., Ong, R. A., Otte, N., Park, N., Perkins, J., Pichel, A., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Telezhinsky, I., Tucci, J. V., Tyler, J., Wakely, S. P., Weinstein, A., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Razzaque, S., Villata, M., Raiteri, C. M., Aller, H. D., Aller, M. F., Larionov, V. M., Arkharov, A. A., Blinov, D. A., Efimova, N. V., Grishina, T. S., Hagen Thorn, V. A., Kopatskaya, E. N., Larionova, L. V., Larionova, E. G., Morozova, D. A., Troitsky, I. S., Ligustri, R., Calcidese, P., Berdyugin, A., Kurtanidze, O. M., Nikolashvili, M. G., Kimeridze, G. N., Sigua, L. A., Kurtanidze, S. O., Chigladze, R. A., Chen, W. P., Koptelova, E., Sakamoto, T., Sadun, A. C., Moody, J. W., Pace, C., Pearson, R., Yatsu, Y., Mori, Y., Carraminyana, A., Carrasco, L., De La Fuente, E., Norris, J. P., Smith, P. S., Wehrle, A., Gurwell, M. A., Zook, A., Pagani, C., Perri, M., Capalbi, M., Cesarini, A., Krimm, H. A., Kovalev, Y. Y., Kovalev, Y. u. A., Ros, E., Pushkarev, A. B., Lister, M. L., Sokolovsky, K. V., Kadler, M., Piner, G., Lã¤hteenmã¤ki, A., Tornikoski, M., Angelakis, E., Krichbaum, T. P., Nestoras, I., Fuhrmann, L., Zensus, J. A., Cassaro, P., Orlati, A., Maccaferri, G., Leto, P., Giroletti, M., Richards, J. L., Max Moerbeck, W., and Readhead, A. C. S.

Subjects
extragalactic background light, multiwavelength observations, Astrophysics::High Energy Astrophysical Phenomena, bl-lacertae objects, Galaxies: BL Lacertae objects: individual: Markarian 501, Methods: data analysis, observational, Polarization, spectral energy-distribution, Flux, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, individual: Markarian 501 [BL Lacertae objects], law, Coincident, 0103 physical sciences, ddc:530, MAGIC (telescope), crab-nebula, Blazar, data analysis [Methods], 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), tev blazars, 010308 nuclear & particles physics, stochastic acceleration, telescope observations, Institut für Physik und Astronomie, Astronomy and Astrophysics, Astronomy and Astrophysic, gamma-ray emission, methods: data analysis, BL Lacertae objects: individual: Markarian 501, Synchrotron, data analysi [Methods], Space and Planetary Science, x-ray, ddc:520, Electrónica, Física nuclear, Electricidad, Degeneracy (mathematics), Astrophysics - High Energy Astrophysical Phenomena, Flare, BL Lac object
Abstract

Astronomy and astrophysics 603, A31 (2017). doi:10.1051/0004-6361/201629540, We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fermi-LAT to cover the γ-ray range from 0.1 GeV to 20 TeV; RXTE and Swift to cover wavelengths from UV tohard X-rays; and GASP-WEBT, which provides coverage of radio and optical wavelengths. Optical polarization measurements were provided for a fraction of the campaign by the Steward and St. Petersburg observatories. We evaluate the variability of the source and interband correlations, the γ-ray flaring activity occurring in May 2009, and interpret the results within two synchrotron self-Compton (SSC) scenarios. Aims. The multiband variability observed during the full campaign is addressed in terms of the fractional variability, and the possible correlations are studied by calculating the discrete correlation function for each pair of energy bands where the significance was evaluated with dedicated Monte Carlo simulations. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters, hence providing a less biased interpretation than the “single-curve SSC model adjustment” typically reported in the literature. Methods. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found on the basis of the acquired data set. The SSC model grid-scan shows that the flaring activity around May 22 cannot be modeled adequately with a one-zone SSC scenario (using an electron energy distribution with two breaks), while it can be suitably described within a two (independent) zone SSC scenario. Here, one zone is responsible for the quiescent emission from the averaged 4.5-month observing period, while the other one, which is spatially separated from the first, dominates the flaring emission occurring at X-rays and very-high-energy (>100 GeV, VHE) γ rays. The flaring activity from May 1, which coincides with a rotation of the electric vector polarization angle (EVPA), cannot be satisfactorily reproduced by either a one-zone or a two-independent-zone SSC model, yet this is partially affected by the lack of strictly simultaneous observations and the presence of large flux changes on sub-hour timescales (detected at VHE γ rays). Results. The higher variability in the VHE emission and lack of correlation with the X-ray emission indicate that, at least during the 4.5-month observing campaign in 2009, the highest energy (and most variable) electrons that are responsible for the VHE γ rays do not make a dominant contribution to the ~1 keV emission. Alternatively, there could be a very variable component contributing to the VHE γ-ray emission in addition to that coming from the SSC scenario. The studies with our dedicated SSC grid-scan show that there is some degeneracy in both the one-zone and the two-zone SSC scenarios probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The observed γ-ray flaring activity, with the EVPA rotation coincident with the first γ-ray flare, resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties., Published by EDP Sciences, Les Ulis

Published
2016
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44. Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

Author

E. Moretti, Alessandro Carosi, D. Nakajima, Kyoshi Nishijima, Arka Chatterjee, C. M. Raiteri, Nikola Godinovic, Benito Marcote, D. Fidalgo, Jose Miguel Miranda, D. Dominis Prester, Yusuke Konno, B. Jordan, Aaron Dominguez, L. Perri, Elena G. Larionova, Marina Manganaro, Kari Nilsson, Pratik Majumdar, M. V. Fonseca, Wen Ping Chen, M. Will, A. La Barbera, D. Galindo, R. Zanin, Merja Tornikoski, Mosè Mariotti, Dario Hrupec, K. Kodani, S. N. Shore, Louis Antonelli, D. Eisenacher Glawion, Max Ludwig Ahnen, X. Paredes-Fortuny, M. Nievas Rosillo, J. E. Ward, A. González Muñoz, Adrian Biland, A.-K. Overkemping, Razmik Mirzoyan, U. Barres de Almeida, J. Palacio, Dmitry A. Blinov, G. Pedaletti, M. A. Lopez, Juri Poutanen, Konstancja Satalecka, Sofia O. Kurtanidze, Michele Doro, U. Menzel, J. M. Paredes, S. Bonnefoy, Givi N. Kimeridze, Thomas Bretz, E. N. Kopatskaya, M. H. Wu, Antonio Stamerra, K. Frantzen, J. Rico, M. Villata, P. Giammaria, Damir Lelas, Alexander Hahn, Y. Hanabata, E. Forné, F. Di Pierro, Jose Luis Contreras, H. C. Lin, R. López-Coto, I. Snidaric, Daniela Dorner, Dariusz Gora, A. Niedzwiecki, F. Borracci, Gareth Hughes, P. Antoranz, Juan Abel Barrio, Juan Cortina, Saverio Lombardi, L. V. Larionova, Ivan S. Troitsky, David Paneque, Dorota Sobczyńska, P. Temnikov, S. Paiano, Karl Mannheim, B. Biasuzzi, M. Gaug, J. Herrera, Talvikki Hovatta, Junko Kushida, Diego F. Torres, Wolfgang Rhode, D. Guberman, Koji Noda, Elisa Bernardini, M. G. Nikolashvili, P. Da Vela, Francesco Longo, J. Hose, D. Garrido Terrats, J. Becerra González, E. Prandini, A. De Angelis, A. Treves, D. Elsaesser, Vitaly Neustroev, D. Hadasch, Julia Thaele, P. G. Prada Moroni, R. Clavero, Markus Garczarczyk, Valeri M. Larionov, R. Ligustri, H. Takami, W. Bednarek, Julian Sitarek, Fabrizio Tavecchio, J. A. Ros, Abelardo Moralejo, M. Palatiello, Stefano Ansoldi, A. C. Sadun, C. Schultz, Vassil Verguilov, G. Maneva, B. Banerjee, S. Buson, Riccardo Paoletti, T. Steinbring, C. Fruck, Lorand A. Sigua, W. Idec, Ivica Puljak, Francesco Dazzi, A. Fernández-Barral, Pierre Colin, Oscar Blanch, T. S. Grishina, Ana Babić, E. de Oña Wilhelmi, E. Colombo, T. Toyama, O. M. Kurtanidze, G. Bonnoli, Elina Lindfors, Anne Lähteenmäki, M. Hayashida, D. A. Morozova, L. O. Takalo, Masahiro Teshima, Ekaterina Koptelova, A. Sillanpää, B. De Lotto, Ievgen Vovk, L. Maraschi, Tomislav Terzić, T. Schweizer, Reiko Orito, Daniel Mazin, Marc Ribó, P. Bangale, Hidetoshi Kubo, Stefano Covino, Tomoki Saito, D. Tescaro, M. Makariev, B. McBreen, M. I. Martínez, Sabrina Einecke, J. Rodriguez Garcia, K. Mallot, R. J. García López, Massimo Persic, Lluis Font, Marcel Strzys, N. V. Efimova, L. Nogués, Universitat de Barcelona, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., Barres De Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Buson, S., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., De Oña Wilhelmi, E., Di Pierro, F., Domínguez, A., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Eisenacher Glawion, D., Elsaesser, D., Fernández Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., García López, R. J., Garczarczyk, M., Garrido Terrats, D., Gaug, M., Giammaria, P., Godinović, N., González Muñoz, A., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, Francesco, López, M., López Coto, R., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moretti, E., Nakajima, D., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nilsson, K., Nishijima, K., Noda, K., Nogués, L., Orito, R., Overkemping, A, Paiano, S., Palacio, J., Palatiello, Michele, Paneque, D., Paoletti, R., Paredes, J. M., Paredes Fortuny, X., Pedaletti, G., Perri, L., Persic, M., Poutanen, J., Prada Moroni, P. G., Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Rodriguez Garcia, J., Saito, T., Satalecka, K., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Blinov, D. A., Chen, W. P., Efimova, N. V., Forné, E., Grishina, T. S., Hovatta, T., Jordan, B., Kimeridze, G. N., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Ligustri, R., Lin, H. C., Mcbreen, B., Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Ros, J. A., Sadun, A. C., Sigua, L. A., Tornikoski, M., Troitsky, I. S., Villata, M., Department of Radio Science and Engineering, Aalto-yliopisto, and Aalto University

Subjects
Astrofísica, Astroparticle physics, BL Lacertae objects: individual: Markarian 421, Radiation mechanisms: non-thermal, Astronomy and Astrophysics, Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Flux, Astrophysics, Astroparticle physic, individual: Markarian 421 [BL Lacertae objects], 01 natural sciences, Radiació, law.invention, Telescope, law, 0103 physical sciences, MAGIC (telescope), Blazar, 010303 astronomy & astrophysics, Cherenkov radiation, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, non-thermal [Radiation mechanisms], Radiation, 010308 nuclear & particles physics, Compton scattering, Astronomy and Astrophysic, Light curve, Astrophysics - Astrophysics of Galaxies, astroparticle physics / BL Lacertae objects: individual: Markarian 421 / radiation mechanisms: non-thermal, Astrophysics of Galaxies (astro-ph.GA), ddc:520, Electrónica, Física nuclear, Electricidad, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year time scales, which can bring additional insight on the processes responsible for its broadband emission. We observed Mrk 421 in the very high energy (VHE) gamma-ray range with the Cherenkov telescope MAGIC-I from March 2007 to June 2009 for a total of 96 hours of effective time after quality cuts. The VHE flux variability is quantified with several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes for the first time. The 2.3 year long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Mets\"ahovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year time scales. Mrk 421 was found in different gamma-ray emission states during the 2.3 year long observation period. Flares and different levels of variability in the gamma-ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Mets\"ahovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. The fractional variability is overall increasing with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and gamma-ray photons are either the same, as expected in the Synchrotron-Self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades., Comment: Corresponding authors: Ann-Kristin Overkemping (ann-kristin.overkemping@tu-dortmund.de), Marina Manganaro (manganaro@iac.es), Diego Tescaro (diego.tescaro@gmail.com), To be published in Astronomy&Astrophysics (A&A), 12 pages, 9 figures

Published
2016

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