Search

Your search keyword '"Larionova, E. G."' showing total 238 results
Start Over Author "Larionova, E. G."
238 results on '"Larionova, E. G."'

1. A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour

Author

Raiteri, C. M., Villata, M., Carnerero, M. I., Kurtanidze, S. O., Mirzaqulov, D. O., Benítez, E., Bonnoli, G., Carosati, D., Acosta-Pulido, J. A., Agudo, I., Andreeva, T. S., Apolonio, G., Bachev, R., Borman, G. A., Bozhilov, V., Brown, L. F., Carbonell, W., Casadio, C., Chen, W. P., Damljanovic, G., Ehgamberdiev, S. A., Elsaesser, D., Escudero, J., Feige, M., Fuentes, A., Gabellini, D., Gazeas, K., Giroletti, M., Grishina, T. S., Gupta, A. C., Gurwell, M. A., Hagen-Thorn, V. A., Hamed, G. M., Hiriart, D., Hodges, M., ivanidze, R. Z., Ivanov, D. V., Joner, M. D., Jorstad, S. G., Jovanovic, M. D., Kiehlmann, S., Kimeridze, G. N., Kopatskaya, E. N., Kovalev, Yu. A., Kovalev, Y. Y., Kurtanidze, O. M., Kurtenkov, A., Larionova, E. G., Lessing, A., Lin, H. C., López, J. M., Lorey, C., Ludwig, J., Marchili, N., Marchini, A., Marscher, A. P., Matsumoto, K., Max-Moerbeck, W., Mihov, B., Minev, M., Mingaliev, M. G., Modaressi, A., Morozova, D. A., Mortari, F., Mufakharov, T. V., Myserlis, I., Nikolashvili, M. G., Pearson, T. J., Popkov, A. V., Rahimov, I. A., Readhead, A. C. S., Reinhart, D., Reeves, R., Righini, S., Romanov, F. D., Savchenko, S. S., Semkov, E., Shishkina, E. V., Sigua, L. A., Slavcheva-Mihova, L., Sotnikova, Yu. V., Steineke, R., Stojanovic, M., Strigachev, A., Takey, A., Traianou, E., Troitskaya, Yu. V., Troitskiy, I. S., Tsai, A. L., Valcheva, A., Vasilyev, A. A., Verna, G., Vince, O., Vrontaki, K., Weaver, Z. R., Webb, J., Yuldoshev, Q. X., Zaharieva, E., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019-2022, together with radio data from the WEBT and other teams, and gamma-ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and gamma-ray brightness maxima. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and gamma-ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The gamma-ray emitting region is found to be co-spatial with the optical one, and the analysis of the gamma-optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability., Comment: In press for A&A

Published
2024

2. The Method of Searching for Rotations of the Polarization Position Angle of Quasars

Author

Savchenko, S. S., Morozova, D. A., Jorstad, S. G., Blinov, D. A., Borman, G. A., Vasilyev, A. A., Grishina, T. S., Zhovtan, A. V., Kopatskaya, E. N., Larionova, E. G., Troitskiy, I. S., Troitskaya, Yu. V., Shishkina, E. V., and Shkodkina, E. A.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Observations of quasars show that the polarization position angle of the emission coming from them varies greatly over time, including periods called rotations during which the angle changes in an orderly manner. The study proposes a method for identifying such events and assessing their statistical significance. The operation of the method is demonstrated using the example of long-term polarimetric observations of the blazars CTA 102, 3C 454.3, and OT 081. During the analysis of light curves, 51 rotations of the polarization position angle were found and it was shown that for CTA 102 and 3C 454.3 the rotations are predominantly oriented in one direction., Comment: 21 pages, 12 figures

Published
2024
Full Text
View/download PDF

3. 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
Full Text
View/download PDF

4. 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
Full Text
View/download PDF

5. Optical circular polarization of blazar S4 0954+65 during high linear polarized states

Author

Liodakis, I., Shablovinskaya, E., Blinov, D., Savchenko, S. S., Malygin, E., Kotov, S., Kiehlmann, S., Readhead, A. C. S., Potter, S. B., Rieger, F. M., Grishina, T. S., Hagen-Thorn, V. A., Kopatskaya, E. N., Larionova, E. G., Morozova, D. A., Troitskiy, I. S., Troitskaya, Y. V., Vasilyev, A. A., Zhovtan, A. V., and Borman, G. A.

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

Optical circular polarization observations can directly test the particle composition in black holes jets. Here we report on the first observations of the BL Lac type object S4 0954+65 in high linear polarized states. While no circular polarization was detected, we were able to place upper limits of <0.5% at the 99.7% confidence. Using a simple model and our novel optical circular polarization observations we can constrain the allowed parameter space for the magnetic field strength and composition of the emitting particles. Our results favor models that require magnetic field strengths of only a few Gauss and models where the jet composition is dominated by electron-positron pairs. We discuss our findings in the context of typical magnetic field strength requirements for blazar emission models., Comment: 4 pages, 1 figure, 1 table, accepted for publication in A&A letters

Published
2023

6. Quasi-simultaneous Optical Flux and Polarization Variability of the Binary Super Massive Black Hole Blazar OJ 287 from 2015 to 2023: Detection of an Anticorrelation in Flux and Polarization Variability

Author

Gupta, Alok C., Kushwaha, Pankaj, Valtonen, Mauri J., Savchenko, Sergey S., Jorstad, Svetlana G., Imazawa, Ryo, Wiita, Paul J., Gu, Minfeng, Marscher, Alan P., Zhang, Zhongli, Bachev, Rumen, Borman, G. A., Gaur, Haritma, Grishina, T. S., Hagen-Thorn, V. A., Kopatskaya, E. N., Larionov, V. M., Larionova, E. G., Larionova, L. V., Morozova, D. A., Nakaoka, T., Strigachev, A., Troitskaya, Yulia V., Troitsky, I. S., Uemura, M., Vasilyev, A. A., Weaver, Z. R., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We study the optical flux and polarization variability of the binary black hole blazar OJ 287 using quasi-simultaneous observations from 2015 to 2023 carried out using telescopes in the USA, Japan, Russia, Crimea, and Bulgaria. This is one of the most extensive quasi-simultaneous optical flux and polarization variability studies of OJ 287. OJ 287 showed large amplitude, ~3.0 mag flux variability, large changes of ~37% in degree of polarization, and a large swing of ~215 degrees in the angle of the electric vector of polarization. During the period of observation, several flares in flux were detected. Those flares are correlated with a rapid increase in the degree of polarization and swings in electric vector of polarization angle. A peculiar behavior of anticorrelation between flux and polarization degree, accompanied by a nearly constant polarization angle, was detected from JD 2,458,156 to JD 2,458,292. We briefly discuss some explanations for the flux and polarization variations observed in OJ 287., Comment: 14 pages, 4 figures, 2 tables, Published in Astrophysical Journal Letters, 2023 November 1

Published
2023
Full Text
View/download PDF

7. The Repeating Flaring Activity of Blazar AO 0235+164

Author

Pedrosa, Juan Escudero, Agudo, Iván, Tramacere, Andrea, Marscher, Alan P., Jorstad, Svetlana, Weaver, Z. R., Casadio, Carolina, Thum, Clemens, Myserlis, Ioannis, Fuentes, Antonio, Traianou, Efthalia, Kim, Jae-Young, Kramer, Joana, López-Coto, Rubén, D'Ammando, Filippo, Bernardos, M., Bonnoli, Giacomo, Blinov, Dmitriy A., Borman, G. A., Grishina, T. S., Hagen-Thorn, V. A., Kopatskaya, E. N., Larionova, E. G., Larionov, V. M., Larionova, L. V., Morozova, D. A., Savchenko, S. S., Troitskiy, I. S., Troitskaya, Y. V., and Vasilyev, A. A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Context. Blazar AO 0235+164, located at redshift z = 0.94, has undergone several sharp multi-spectral-range flaring episodes during the last decades. In particular, the episodes peaking in 2008 and 2015, that received extensive multi-wavelength coverage, exhibited interesting behavior. Aims. We study the actual origin of these two observed flares by constraining the properties of the observed photo-polarimetric variability, those of the broad-band spectral energy-distribution and the observed time-evolution behavior of the source as seen by ultra-high resolution total-flux and polarimetric Very-long-baseline interferometry (VLBI) imaging. Methods. The analysis of VLBI images allows us to constrain kinematic and geometrical parameters of the 7 mm jet. We use the Discrete Correlation Function to compute the statistical correlation and the delays between emission at different spectral ranges. Multi-epoch modeling of the spectral energy distributions allows us to propose specific models of emission; in particular for the unusual spectral features observed in this source in the X-ray region of the spectrum during strong multi spectral-range flares. Results. We find that these X-ray spectral features can be explained by an emission component originating in a separate particle distribution than the one responsible for the two standard blazar bumps. This is in agreement with the results of our correlation analysis that do not find a strong correlation between the X-rays and the remaining spectral ranges. We find that both external Compton dominated and synchrotron self-Compton dominated models can explain the observed spectral energy distributions. However, synchrotron self-Compton models are strongly favored by the delays and geometrical parameters inferred from the observations.

Published
2023
Full Text
View/download PDF

8. 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

9. 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
Full Text
View/download PDF

10. 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
Full Text
View/download PDF

11. 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
Full Text
View/download PDF

12. Parameters of the type-IIP supernova SN 2012aw

Author

Nikiforova, A. A., Baklanov, P. V., Blinnikov, S. I., Blinov, D. A., Grishina, T. S., Troitskaya, Yu. V., Morozova, D. A., Kopatskaya, E. N., Larionova, E. G., and Troitsky, I. S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results the photometric observations of the Type IIP supernova SN 2012aw obtained for the time interval from 7 till 371 days after the explosion. Using the previously published values of the photospheric velocities we've computed the hydrodynamic model which simultaneously reproduced the photometry observations and velocity measurements. The model was calculated with the multi-energy group radiation hydrodynamics code STELLA. We found the parameters of the pre-supernova: radius $R = 500 R_\odot$, nickel mass $M(^{56}$Ni$)$ $\sim 0.06 M_\odot$, pre-supernova mass $25 M_\odot$, mass of ejected envelope $23.6 M_\odot$, explosion energy $E \sim 2 \times 10^{51}$ erg. The model progenitor mass $M=25 M_\odot$ significantly exceeds the upper limit mass $M=17 M_\odot$, obtained from analysis the pre-SNe observations. This result confirms once more that the 'Red Supergiant Problem' must be resolved by stellar evolution and supernova explosion theories in interaction with observations., Comment: 7 pages, 8 figures, 3 tables. Accepted for publication in MNRAS

Published
2021
Full Text
View/download PDF

13. Short-Timescale Variability of the Blazar Mrk 421 from AstroSat and Simultaneous Multi-Wavelength Observations

Author

Chatterjee, Ritaban, Das, Susmita, Khasnovis, Archishman, Ghosh, Ritesh, Kumari, Neeraj, Naik, Sachindra, Larionov, V. M., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Nikiforova, A. A., Morozov, D. A., 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 study the multi-wavelength variability of the blazar Mrk 421 at minutes to days timescales using simultaneous data at $\gamma$-rays from Fermi, 0.7-20 keV energies from AstroSat, and optical and near-infrared (NIR) wavelengths from ground-based observatories. We compute the shortest variability timescales at all of the above wavebands and find its value to be ~1.1 ks at the hard X-ray energies and increasingly longer at soft X-rays, optical and NIR wavelengths as well as at the GeV energies. We estimate the value of the magnetic field to be 0.5 Gauss and the maximum Lorentz factor of the emitting electrons ~1.6 x $10^5$ assuming that synchrotron radiation cooling drives the shortest variability timescale. Blazars vary at a large range of timescales often from minutes to years. These results, as obtained here from the very short end of the range of variability timescales of blazars, are a confirmation of the leptonic scenario and in particular the synchrotron origin of the X-ray emission from Mrk 421 by relativistic electrons of Lorentz factor as high as $10^5$. This particular mode of confirmation has been possible using minutes to days timescale variability data obtained from AstroSat and simultaneous multi-wavelength observations., Comment: 8 pages, 2 figures, accepted for publication in the Journal of Astrophysics and Astronomy

Published
2021
Full Text
View/download PDF

14. VHE gamma-ray detection of FSRQ QSO B1420+326 and modeling of its enhanced broadband state in 2020

Author

Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., 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., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Ferrara, G., Foffano, L., 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., 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., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., 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., Ninci, D., 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., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., 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., Torres-Albà, N., Tosti, L., Truzzi, S., Tutone, A., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Zarić, D., Angioni, R., D'Ammando, F., Ciprini, S., Cheung, C. C., Orienti, M., Pacciani, L., Prajapati, P., Kumar, P., Ganesh, S., Kurtenkov, A., Marchini, A., Carrasco, L., Escobedo, G., Porras, A., Recillas, E., Lähteenmäki, A., Tornikoski, M., Berton, M., Tammi, J., Vera, R. J. C., Jorstad, S. G., Marscher, A. P., Weaver, Z. R., Hart, M., Hallum, M. K., Larionov, V. M., Borman, G. A., Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Nikiforova, A. A., Morozova, D. A., Savchenko, S. S., Troitskaya, Yu. V., Troitsky, I. S., Vasilyev, A. A., Hodges, M., Hovatta, T., Kiehlmann, S., Max-Moerbeck, W., Readhead, A. C. S., Reeves, R., and Pearson, T. J.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Context. QSO B1420+326 is a blazar classified as a Flat Spectrum Radio Quasar (FSRQ). In the beginning of 2020 it underwent an enhanced flux state. An extensive multiwavelength campaign allowed us to trace the evolution of the flare. Aims. We search for VHE gamma-ray emission from QSO B1420+326 during this flaring state. We aim to characterize and model the broadband emission of the source over different phases of the flare. Methods. The source was observed with a number of instruments in radio, near infrared, optical (including polarimetry and spectroscopy), ultra-violet, X-ray and gamma-ray bands. We use dedicated optical spectroscopy results to estimate the accretion disk and the dust torus luminosity. We perform spectral energy distribution modeling in the framework of combined Synchrotron-Self-Compton and External Compton scenario in which the electron energy distribution is partially determined from acceleration and cooling processes. Results. During the enhanced state the flux of both SED components drastically increased and the peaks were shifted to higher energies. Follow up observations with the MAGIC telescopes led to the detection of very-high-energy gamma-ray emission from this source, making it one of only a handful of FSRQs known in this energy range. Modeling allows us to constrain the evolution of the magnetic field and electron energy distribution in the emission region. The gamma-ray flare was accompanied by a rotation of the optical polarization vector during a low polarization state. Also, a new, superluminal radio knot contemporaneously appeared in the radio image of the jet. The optical spectroscopy shows a prominent FeII bump with flux evolving together with the continuum emission and a MgII line with varying equivalent width., Comment: 20 pages, 15 figures, 7 tables, accepted for publication in A&A

Published
2020
Full Text
View/download PDF

15. Two Flares with One Shock: the Interesting Case of 3C 454.3

Author

Liodakis, I., Blinov, D., Jorstad, S. G., Arkharov, A. A., Di Paola, A., Efimova, N. V., Grishina, T. S., Kiehlmann, S., Kopatskaya, E. N., Larionov, V. M., Larionova, L. V., Larionova, E. G., Marscher, A. P., Morozova, D. A., Nikiforova, A. A., Pavlidou, V., Traianou, E., Troitskaya, Yu. V., Troitsky, I. S., Uemura, M., and Weaver, Z. R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The quasar 3C 454.3 is a blazar known for its rapid and violent outbursts seen across the electromagnetic spectrum. Using gamma-ray, X-ray, multi-band optical, and very long baseline interferometric data we investigate the nature of two such events that occurred in 2013 and 2014 accompanied by strong variations in optical polarization, including a 230 degree electric vector position angle (EVPA) rotation. Our results suggest that a single disturbance was responsible for both flaring events. We interpret the disturbance as a shock propagating down the jet. Under this interpretation the 2013-flare originated most likely due to changes in the viewing angle caused by perhaps a bent or helical trajectory of the shock upstream of the radio core. The 2014-flare and optical polarization behavior are the result of the shock exiting the 43 GHz radio core, suggesting that shock crossings are one of the possible mechanisms for EVPA rotations., Comment: 14 pages, 10 figures, 2 Tables, accepted for publication in The Astrophysical Journal

Published
2020
Full Text
View/download PDF

16. 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

17. 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
Full Text
View/download PDF

18. 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
Full Text
View/download PDF

19. 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
Full Text
View/download PDF

20. Quasi-periodic behaviour in the optical and {\gamma}-ray light curves of blazars 3C 66A and B2 1633+38

Author

Otero-Santos, J., Acosta-Pulido, J. A., González, J. Becerra, Raiteri, C. M., Larionov, V. M., Peñil, P., Smith, P. S., Niebla, C. Ballester, Borman, G. A., Carnerero, M. I., Segura, N. Castro, Grishina, T. S., Kopatskaya, E. N., Larionova, E. G., Morozova, D. A., Nikiforova, A. A., Savchenko, S. S., Troitskaya, Yu. V., Troitsky, I. S., Vasilyev, A. A., and Villata, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on quasi-periodic variability found in two blazars included in the Steward Observatory Blazar Monitoring data sample: the BL Lac object 3C 66A and the Flat Spectrum Radio Quasar B2 1633+38. We collect optical photometric and polarimetric data in V and R bands of these sources from different observatories: St. Petersburg University, Crimean Astrophysical Observatory, WEBT-GASP, Catalina Real-Time Transient Survey, Steward Observatory, STELLA Robotic Observatory and Katzman Automatic Imaging Telescope. In addition, an analysis of the $\gamma$-ray light curves from $\textit{Fermi}$-LAT is included. Three methods are used to search for any periodic behaviour in the data: the Z-transform Discrete Correlation Function, the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform. We find evidences of possible quasi-periodic variability in the optical photometric data of both sources with periods of $\sim$3 years for 3C 66A and $\sim$1.9 years for B2 1633+38, with significances between 3$\sigma$ and 5$\sigma$. Only B2 1633+38 shows evidence of this behaviour in the optical polarized data set at a confidence level of 2$\sigma$-4$\sigma$. This is the first reported evidence of quasi-periodic behaviour in the optical light curve of B2 1633+38. Also a hint of quasi-periodic behaviour is found in the $\gamma$-ray light curve of B2 1633+38 with a confidence level $\geqslant$2$\sigma$, while no periodicity is observed for 3C 66A in this energy range. We propose different jet emission models that could explain the quasi-periodic variability and the differences found between these two sources., Comment: Accepted for publication in MNRAS

Published
2020
Full Text
View/download PDF

21. 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
Full Text
View/download PDF

22. Rapid quasi-periodic oscillations in the relativistic jet of BL Lacertae

Author

Jorstad, S. G., Marscher, A. P., Raiteri, C. M., Villata, M., Weaver, Z. R., Zhang, H., Dong, L., Gómez, J. L., Perel, M. V., Savchenko, S. S., Larionov, V. M., Carosati, D., Chen, W. P., Kurtanidze, O. M., Marchini, A., Matsumoto, K., Mortari, F., Aceti, P., Acosta-Pulido, J. A., Andreeva, T., Apolonio, G., Arena, C., Arkharov, A., Bachev, R., Banfi, M., Bonnoli, G., Borman, G. A., Bozhilov, V., Carnerero, M. I., Damljanovic, G., Ehgamberdiev, S. A., Elsässer, D., Frasca, A., Gabellini, D., Grishina, T. S., Gupta, A. C., Hagen-Thorn, V. A., Hallum, M. K., Hart, M., Hasuda, K., Hemrich, F., Hsiao, H. Y., Ibryamov, S., Irsmambetova, T. R., Ivanov, D. V., Joner, M. D., Kimeridze, G. N., Klimanov, S. A., Knött, J., Kopatskaya, E. N., Kurtanidze, S. O., Kurtenkov, A., Kuutma, T., Larionova, E. G., Leonini, S., Lin, H. C., Lorey, C., Mannheim, K., Marino, G., Minev, M., Mirzaqulov, D. O., Morozova, D. A., Nikiforova, A. A., Nikolashvili, M. G., Ovcharov, E., Papini, R., Pursimo, T., Rahimov, I., Reinhart, D., Sakamoto, T., Salvaggio, F., Semkov, E., Shakhovskoy, D. N., Sigua, L. A., Steineke, R., Stojanovic, M., Strigachev, A., Troitskaya, Y. V., Troitskiy, I. S., Tsai, A., Valcheva, A., Vasilyev, A. A., Vince, O., Waller, L., Zaharieva, E., and Chatterjee, R.

Published
2022
Full Text
View/download PDF

23. 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
Full Text
View/download PDF

24. 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
Full Text
View/download PDF

25. 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
Full Text
View/download PDF

26. Exceptional outburst of the blazar CTA 102 in 2012: The GASP-WEBT campaign and its extension

Author

Larionov, V. M., Villata, M., Raiteri, C. M., Jorstad, S. G., Marscher, A. P., Agudo, I., Smith, P. S., Acosta-Pulido, J. A., Arévalo, M. J., Arkharov, A. A., Bachev, R., Blinov, D. A., Borisov, G., Borman, G. A., Bozhilov, V., Bueno, A., Carnerero, M. I., Carosati, D., Casadio, C., Chen, W. P., Clemens, D. P., Di Paola, A., Ehgamberdiev, Sh. A., Gómez, J. L., González-Morales, P. A, Griñón-Marín, A., Grishina, T. S., Hagen-Thorn, V. A., Ibryamov, S., Itoh, R., Kopatskaya, E. N., Koptelova, E., Lázaro, C., Larionova, E. G., Larionova, L. V., Manilla-Robles, A., Metodieva, Y., Milanova, Yu. V., Mirzaqulov, D. O., Molina, S. N., Morozova, D. A., Nazarov, S. V., Ovcharov, E., Peneva, S., Ros, J. A., Sadun, A. C., Savchenko, S. S., Semkov, E., Sergeev, S. G., Strigachev, A., Troitskaya, Yu. V., and Troitsky, I. S.

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

After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from gamma-ray to near-infrared frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive GASP-WEBT collaboration campaign in optical and NIR bands, with an addition of previously unpublished archival data and extension through fall 2015, allows comparison of this outburst with the previous activity period of this blazar in 2004-2005. We find remarkable similarity between the optical and gamma-ray behaviour of CTA 102 during the outburst, with a time lag between the two light curves of ~1 hour, indicative of co-spatiality of the optical and gamma-ray emission regions. The relation between the gamma-ray and optical fluxes is consistent with the SSC mechanism, with a quadratic dependence of the SSC gamma-ray flux on the synchrotron optical flux evident in the post-outburst stage. However, the gamma-ray/optical relationship is linear during the outburst; we attribute this to changes in the Doppler factor. A strong harder-when-brighter spectral dependence is seen both the in gamma-ray and optical non-thermal emission. This hardening can be explained by convexity of the UV-NIR spectrum that moves to higher frequencies owing to an increased Doppler shift as the viewing angle decreases during the outburst stage. The overall pattern of Stokes parameter variations agrees with a model of a radiating blob or shock wave that moves along a helical path down the jet., Comment: 11 pages, 14 figures, accepted in MNRAS

Published
2016
Full Text
View/download PDF

27. 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
Full Text
View/download PDF

28. 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
Full Text
View/download PDF

29. 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
Full Text
View/download PDF

30. 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
Full Text
View/download PDF

32. Optical circular polarization of blazar S4 0954+65 during high linear polarized states

Author

Liodakis, I., primary, Shablovinskaya, E., additional, Blinov, D., additional, Savchenko, S. S., additional, Malygin, E., additional, Kotov, S., additional, Kiehlmann, S., additional, Readhead, A. C. S., additional, Potter, S. B., additional, Rieger, F. M., additional, Grishina, T. S., additional, Hagen-Thorn, V. A., additional, Kopatskaya, E. N., additional, Larionova, E. G., additional, Morozova, D. A., additional, Troitskiy, I. S., additional, Troitskaya, Y. V., additional, Vasilyev, A. A., additional, Zhovtan, A. V., additional, and Borman, G. A., additional

Published
2023
Full Text
View/download PDF

33. The Outburst of the Blazar S40954+658 in March-April 2011

Author

Morozova, D. A., Larionov, V. M., Troitsky, I. S., Jorstad, S. G., Marscher, A. P., Gómez, J. L., Blinov, D. A., Efimova, N. V., Hagen-Thorn, V. A., Hagen-Thorn, E. I., Joshi, M., Konstantinova, T. S., Kopatskaya, E. N., Larionova, L. V., Larionova, E. G., Lähteenmäki, A., Tammi, J., Rastorgueva-Foi, E., McHardy, I., Tornikoski, M., Agudo, I., Casadio, C., Molina, S. N., Volvach, A. E., and Volvach, L. N.

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

We present the results of optical (R band) photometric and polarimetric monitoring and Very Long Baseline Array (VLBA) imaging of the blazar S4 0954+658, along with Fermi and gamma;-ray data during a multi-waveband outburst in 2011 March-April. After a faint state with a brightness level R ~17.6 mag registered in the first half of January 2011, the optical brightness of the source started to rise and reached ~14.8 mag during the middle of March, showing flare-like behavior. The most spectacular case of intranight variability was observed during the night of 2011 March 9, when the blazar brightened by ~0.7 mag within ~7 hours. During the rise of the flux the position angle of optical polarization rotated smoothly over more than 300$\deg$. At the same time, within 1$\sigma$ uncertainty a new superluminal knot appeared with an apparent speed of 19.0$\pm$0.3 c. We have very strong evidence for association of this knot with the multi-waveband outburst in 2011 March-April. We also analyze the multi-frequency behavior of S4 0954+658 during a number of minor outbursts from August 2008 to April 2012. We find some evidence of connections between at least two more superluminal ejecta and near-simultaneous optical flares., Comment: 9 pages, 10 figures, accepted for publication in The Astronomical Journal

Published
2014
Full Text
View/download PDF

34. 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
Full Text
View/download PDF

35. 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
Full Text
View/download PDF

36. The Outburst of the Blazar S5 0716+71 in 2011 October: Shock in a Helical Jet

Author

Larionov, V. M., Jorstad, S. G., Marscher, A. P., Morozova, D. A., Blinov, D. A., Hagen-Thorn, V. A., Konstantinova, T. S., Kopatskaya, E. N., Larionova, L. V., Larionova, E. G., and Troitsky, I. S.

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

We present the results of optical (R band) photometric and polarimetric monitoring and Very Long Baseline Array (VLBA) imaging of the blazar S5 0716+714 along with Fermi gamma-ray data during a multi-waveband outburst in 2011 October. We analyze total and polarized intensity images of the blazar obtained with the VLBA at 43 GHz during and after the outburst. Monotonic rotation of the linear polarization vector at a rate of >50 degrees per night coincided with a sharp maximum in gamma-ray and optical flux. At the same time, within the uncertainties, a new superluminal knot appeared, with an apparent speed of ~21c. The general multi-frequency behavior of the outburst can be explained within the framework of a shock wave propagating along a helical path in the blazar's jet., Comment: 7 pages, 9 figures, accepted for publication in The Astrophysical Journal; minor corrections in the Acknowledgments

Published
2013
Full Text
View/download PDF

37. 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
Full Text
View/download PDF

38. Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

Author

Ackermann, M., Ajello, M., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bottacini, E., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., Casandjian, J. M., Cavazzuti, E., Cecchi, C., Charles, E., Chekhtman, A., Chiang, J., Ciprini, S., Claus, R., Cohen-Tanugi, J., Cutini, S., D'Ammando, F., de Palma, F., Dermer, C. D., Silva, E. do Couto e, Drell, P. S., Drlica-Wagner, A., Dubois, R., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Fortin, P., Fuhrmann, L., Fukazawa, Y., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giglietto, N., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I. A., Guiriec, S., Hadasch, D., Hayashida, M., Hughes, R. E., Itoh, R., Johannesson, G., Johnson, A. S., Katagiri, H., Kataoka, J., Knodlseder, J., Kuss, M., Lande, J., Larsson, S., Lee, S. -H., Longo, F., Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Madejski, G. M., Mazziotta, M. N., McEnery, J. E., Mehault, J., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Naumann-Godo, M., Nishino, S., Norris, J. P., Nuss, E., Ohsugi, T., Okumura, A., Omodei, N., Orlando, E., Ozaki, M., Paneque, D., Panetta, J. H., Pelassa, V., Pesce-Rollins, M., Pierbattista, M., Piron, F., Pivato, G., Porter, T. A., Raino, S., Rando, R., Rastawicki, D., Razzano, M., Readhead, A., Reimer, A., Reimer, O., Reyes, L. C., Richards, J. L., Sbarra, C., Sgro, C., Siskind, E. J., Spandre, G., Spinelli, P., Szostek, A., Takahashi, H., Tanaka, T., Thayer, J. G., Thayer, J. B., Thompson, D. J., Tinivella, M., Torres, D. F., Tosti, G., Troja, E., Usher, T. L., Vandenbroucke, J., Vasileiou, V., Vianello, G., Vitale, V., Waite, A. P., Winer, B. L., Wood, K. S., Yang, Z., Zimmer, S., Moderski, R., Nalewajko, K., Sikora, M., Villata, M., Raiteri, C. M., Aller, H. D., Aller, M. F., Arkharov, A. A., Benitez, E., Berdyugin, A., Blinov, D. A., Boettcher, M., Calle, O. J. A. Bravo, Buemi, C. S., Carosati, D., Chen, W. P., Diltz, C., Di Paola, A., Dolci, M., Efimova, N. V., Forn\', E., Gurwell, M. A., Heidt, J., Hiriart, D., Jordan, B., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Lahteenmaki, A., Larionova, E. G., Larionova, L. V., Larionov, V. M., Leto, P., Lindfors, E., Lin, H. C., Morozova, D. A., Nikolashvili, M. G., Nilsson, K., Oksman, M., Roustazadeh, P., Sievers, A., Sigua, L. A., Sillanpaa, A., Takahashi, T., Takalo, L. O., Tornikoski, M., Trigilio, C., Troitsky, I. S., Umana, G., Angelakis, E., Krichbaum, T. P., Nestoras, I., Riquelme, D., Krips, M., Trippe, S., Arai, A., Kawabata, K. S., Sakimoto, K., Sasada, M., Sato, S., Uemura, M., Yamanaka, M., Yoshida, M., Belloni, T., Tagliaferri, G., Bonning, E. W., Isler, J., Urry, C. M., Hoversten, E., Falcone, A., Pagani, C., and Stroh, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to {\gamma} -ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP- WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the {\gamma} -ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 Rg . We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus., Comment: 48 pages, 8 figures

Published
2012
Full Text
View/download PDF

39. The structure and emission model of the relativistic jet in the quasar 3C 279 inferred from radio to high-energy gamma-ray observations in 2008-2010

Author

Hayashida, M., Madejski, G. M., Nalewajko, K., Sikora, M., Wehrle, A. E., Ogle, P., Collmar, W., Larsson, S., Fukazawa, Y., Itoh, R., Chiang, J., Stawarz, L., Blandford, R. D., Richards, J. L., Max-Moerbeck, W., Readhead, A., Buehler, R., Cavazzuti, E., Ciprini, S., Gehrels, N., Reimer, A., Szostek, A., Tanaka, T., Tosti, G., Uchiyama, Y., Kawabata, K. S., Kino, M., Sakimoto, K., Sasada, M., Sato, S., Uemura, M., Yamanaka, M., Greiner, J., Kruehler, T., Rossi, A., Macquart, J. P., Bock, D. C. -J., Villata, M., Raiteri, C. M., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Benitez, E., Berdyugin, A., Blinov, D. A., Blumenthal, K., Boettcher, M., Buemi, C. S., Carosati, D., Chen, W. P., Di Paola, A., Dolci, M., Efimova, N. V., Forne, E., Gomez, J. L., Gurwell, M. A., Heidt, J., Hiriart, D., Jordan, B., Jorstad, S. G., Joshi, M., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Lahteenmaki, A., Lamerato, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Leto, P., Lindfors, E., Marscher, A. P., McHardy, I. M., Molina, S. N., Morozova, D. A., Nikolashvili, M. G., Nilsson, K., Reinthal, R., Roustazadeh, P., Sakamoto, T., Sigua, L. A., Sillanpaa, A., Takalo, L., Tammi, J., Taylor, B., Tornikoski, M., Trigilio, C., Troitsky, I. S., and Umana, G.

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

We present time-resolved broad-band observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears delayed with respect to the gamma-ray emission by about 10 days. X-ray observations reveal a pair of `isolated' flares separated by ~90 days, with only weak gamma-ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the gamma-ray flare, while the peak appears in the mm/sub-mm band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broad-band spectra during the gamma-ray flaring event by a shift of its location from ~ 1 pc to ~ 4 pc from the central black hole. On the other hand, if the gamma-ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission., Comment: 23 pages, 18 figures 5 tables, Accepted for publication in The Astrophysical Journal

Published
2012
Full Text
View/download PDF

40. Optical Outburst of the Gamma-Ray Blazar S4 0954+658 in March-April 2011

Author

Larionov, V. M., Jorstad, S. G., Marscher, A. P., Morozova, D. A., Troitsky, I. S., Blinov, D. A., Kopatskaya, E. N., and Larionova, E. G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present optical photopolarimetric observations of the BL Lac object S4 0954+658 obtained with the 70-cm telescope in Crimea, 40-cm telescope in St.Petersburg, and 1.8-m Perkins telescope at Lowell Observatory (Flagstaff, Az). After a faint state with a brightness level R ~17.6 mag registered in the first half of January 2011, the optical brightness of the source started to rise and reached ~14.8 mag during the middle of March, showing flare-like behavior. The most spectacular case of intranight variability was observed during the night of 2011 March 9, when the blazar brightened by ~0.7 mag within ~7 hours. During the rise of the flux the position angle of optical polarization rotated smoothly over more than 200 degrees. S4 0954+658 is a gamma-ray blazar with gamma-ray flux of (5{\pm}3)x10^{-10} phot/cm^2/s according to the Fermi 11-month Catalog Extragalactic Sources. Our analysis of contemporaneous Fermi LAT data does not show any sign of increased gamma-ray activity above the detection threshold except for an elevated flux on 2011 March 5, JD2455626, coincident with the local optical maximum., Comment: 2011 Fermi Symposium proceedings - eConf C110509

Published
2011

41. 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
Full Text
View/download PDF

42. Another look at the BL Lacertae flux and spectral variability

Author

Raiteri, C. M., Villata, M., Bruschini, L., Capetti, A., Kurtanidze, O. M., Larionov, V. M., Romano, P., Vercellone, S., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Berdyugin, A., Blinov, D. A., Böttcher, M., Buemi, C. S., Calcidese, P., Carosati, D., Casas, R., Chen, W. -P., Coloma, J., Diltz, C., Di Paola, A., Dolci, M., Efimova, N. V., Forné, E., Gómez, J. L., Gurwell, M. A., Hakola, A., Hovatta, T., Hsiao, H. Y., Jordan, B., Jorstad, S. G., Koptelova, E., Kurtanidze, S. O., Lähteenmäki, A., Larionova, E. G., Leto, P., Lindfors, E., Ligustri, R., Marscher, A. P., Morozova, D. A., Nikolashvili, M. G., Nilsson, K., Ros, J. A., Roustazadeh, P., Sadun, A. C., Sillanpää, A., Sainio, J., Takalo, L. O., Tornikoski, M., Trigilio, C., Troitsky, I. S., and Umana, G.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. The GASP-WEBT observations show an optical flare in 2008 February-March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable. The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate flux variability on an hour time scale. The Swift X-ray data reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distribution (SED) corresponding to the 2008 low-brightness state, which was characterised by a synchrotron dominance, to the 1997 outburst state, where the inverse-Compton emission was prevailing. A fit with an inhomogeneous helical jet model suggests that two synchrotron components are at work with their self inverse-Compton emission. Most likely, they represent the radiation from two distinct emitting regions in the jet. We show that the difference between the source SEDs in 2008 and 1997 can be explained in terms of pure geometrical variations. The outburst state occurred when the jet-emitting regions were better aligned with the line of sight, producing an increase of the Doppler beaming factor. Our analysis demonstrates that the jet geometry can play an extremely important role in the BL Lacertae flux and spectral variability., Comment: 12 pages, 10 figures, accepted for publication in A&A

Published
2010
Full Text
View/download PDF

43. Quasi-simultaneous Optical Flux and Polarization Variability of the Binary Super Massive Black Hole Blazar OJ 287 from 2015 to 2023: Detection of an Anticorrelation in Flux and Polarization Variability

Author

Gupta, Alok C., primary, Kushwaha, Pankaj, additional, Valtonen, Mauri J., additional, Savchenko, Sergey S., additional, Jorstad, Svetlana G., additional, Imazawa, Ryo, additional, Wiita, Paul J., additional, Gu, Minfeng, additional, Marscher, Alan P., additional, Zhang, Zhongli, additional, Bachev, Rumen, additional, Borman, G. A., additional, Gaur, Haritma, additional, Grishina, T. S., additional, Hagen-Thorn, V. A., additional, Kopatskaya, E. N., additional, Larionov, V. M., additional, Larionova, E. G., additional, Larionova, L. V., additional, Morozova, D. A., additional, Nakaoka, T., additional, Strigachev, A., additional, Troitskaya, Yulia V., additional, Troitsky, I. S., additional, Uemura, M., additional, Vasilyev, A. A., additional, Weaver, Z. R., additional, and Zhovtan, A. V., additional

Published
2023
Full Text
View/download PDF

44. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ-ray brightness levels

Author

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

Published
2023
Full Text
View/download PDF

45. Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

Author

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

Published
2023
Full Text
View/download PDF

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

Author

Raiteri, C M, primary, Villata, M, additional, Jorstad, S G, additional, Marscher, A P, additional, Acosta Pulido, J A, additional, Carosati, D, additional, Chen, W P, additional, Joner, M D, additional, Kurtanidze, S O, additional, Lorey, C, additional, Marchini, A, additional, Matsumoto, K, additional, Mirzaqulov, D O, additional, Savchenko, S S, additional, Strigachev, A, additional, Vince, O, additional, Aceti, P, additional, Apolonio, G, additional, Arena, C, additional, Arkharov, A, additional, Bachev, R, additional, Bader, N, additional, Banfi, M, additional, Bonnoli, G, additional, Borman, G A, additional, Bozhilov, V, additional, Brown, L F, additional, Carbonell, W, additional, Carnerero, M I, additional, Damljanovic, G, additional, Dhiman, V, additional, Ehgamberdiev, S A, additional, Elsaesser, D, additional, Feige, M, additional, Gabellini, D, additional, Galán, D, additional, Galli, G, additional, Gaur, H, additional, Gazeas, K, additional, Grishina, T S, additional, Gupta, A C, additional, Hagen-Thorn, V A, additional, Hallum, M K, additional, Hart, M, additional, Hasuda, K, additional, Heidemann, K, additional, Horst, B, additional, Hou, W-J, additional, Ibryamov, S, additional, Ivanidze, R Z, additional, Jovanovic, M D, additional, Kimeridze, G N, additional, Kishore, S, additional, Klimanov, S, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Kushwaha, P, additional, Lane, D J, additional, Larionova, E G, additional, Leonini, S, additional, Lin, H C, additional, Mannheim, K, additional, Marino, G, additional, Minev, M, additional, Modaressi, A, additional, Morozova, D A, additional, Mortari, F, additional, Nazarov, S V, additional, Nikolashvili, M G, additional, Otero Santos, J, additional, Ovcharov, E, additional, Papini, R, additional, Pinter, V, additional, Privitera, C A, additional, Pursimo, T, additional, Reinhart, D, additional, Roberts, J, additional, Romanov, F D, additional, Rosenlehner, K, additional, Sakamoto, T, additional, Salvaggio, F, additional, Schoch, K, additional, Semkov, E, additional, Seufert, J, additional, Shakhovskoy, D, additional, Sigua, L A, additional, Singh, C, additional, Steineke, R, additional, Stojanovic, M, additional, Tripathi, T, additional, Troitskaya, Y V, additional, Troitskiy, I S, additional, Tsai, A, additional, Valcheva, A, additional, Vasilyev, A A, additional, Vrontaki, K, additional, Weaver, Z R, additional, Wooley, J H F, additional, Zaharieva, E, additional, and Zhovtan, A V, additional

Published
2023
Full Text
View/download PDF

47. Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and $γ$-Ray Activity

Author

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

Subjects
ddc:520
Abstract

The astrophysical journal / Supplement series 266(2), 37 (2023). doi:10.3847/1538-4365/acc181, We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) $γ$-rays. A significant correlation (>3σ) between X-rays and VHE $γ$-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 the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy γ-rays and radio, with the radio lagging by more than 100 days, placing the γ-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 $γ$-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 $γ$r 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 toward 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., Published by Institute of Physics Publ., London

Published
2023
Full Text
View/download PDF

48. Blazar spectral variability as explained by a twisted inhomogeneous jet

Author

Raiteri, C. M., Villata, M., Acosta-Pulido, J. A., Agudo, I., Arkharov, A. A., Bachev, R., Baida, G. V., Benítez, 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., DʼAmmando, F., Di Paola, A., Echevarría, J., Efimova, N. V., Ehgamberdiev, Sh. A., Espinosa, C., Fuentes, A., Giunta, A., Gómez, J. L., Grishina, T. S., Gurwell, M. A., Hiriart, D., Jermak, H., Jordan, B., Jorstad, S. G., Joshi, M., Kopatskaya, E. N., Kuratov, K., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Larionova, L. V., Lázaro, C., Lin, C. S., Malmrose, M. P., Marscher, A. P., Matsumoto, K., McBreen, B., Michel, R., Mihov, B., Minev, M., Mirzaqulov, D. O., Mokrushina, A. A., Molina, S. N., Moody, J. W., Morozova, D. A., Nazarov, S. V., Nikolashvili, M. G., Ohlert, J. M., Okhmat, D. 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., 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., and Vince, O.

Published
2017
Full Text
View/download PDF

49. 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
Full Text
View/download PDF

50. Unveiling the complex correlation patterns in Mrk 421

Author

Arbet-Engels, A., Paneque, D., Heckmann, L., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., Barres 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., Biland, A., Blanch, O., Bökenkamp, H., Bonnoli, G., 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., Giacomo D'Amico, D Elia, V., Da Vela, P., Dazzi, F., Angelis, A., 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., Dorner, D., Doro, M., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Fukazawa, Y., 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., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Ishio, K., Iwamura, Y., Jiménez Martínez, I., Jormanainen, J., Jouvin, L., Karjalainen, M., 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., Machado Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Nakamori, T., Nava, L., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paoletti, R., Paredes, J. M., Pavletić, L., Peñil, P., Persic, M., Pihet, M., Prada Moroni, P. G., Prandini, E., Priyadarshi, C., Puljak, I., 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., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Takeishi, R., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Yamamoto, T., Zarić, D., Balbo, M., Bretz, T., Buss, J., Eisenberger, L., Hildebrand, D., Iotov, R., Kalenski, A., 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., and Rizzi, N.

Subjects
Physics, education.field_of_study, Astrophysics::High Energy Astrophysical Phenomena, Population, Flux, Sigma, Astrophysics, Synchrotron, Redshift, law.invention, law, MAGIC (telescope), education, Blazar, Flare
Abstract

The blazar Mrk421 (redshift z=0.031) is one of the brightest and closest BL Lac type objects, making it an ideal target to probe blazar physics. We report on an extensive multi-wavelength observing campaign in 2017, during which the intra-band correlation patterns show some disparity and complex behaviours. Observations from several instruments are used to achieve an optimal temporal coverage from radio to TeV energies. In particular, four multi-hour NuSTAR observations organised simultaneously with MAGIC allow to obtain a precise measurement of the falling segments of the two spectral components. A detailed investigation of the very-high-energy (VHE; >100 GeV) versus X-ray flux correlation is performed, by binning the data into several sub-energy bands. A positively correlated variability is observed, but the correlation characteristics change substantially across the various bands probed. Furthermore, during the simultaneous MAGIC and NuSTAR observations a clear change of the Compton dominance is detected without a simultaneous change in the synchrotron regime, indicating "orphan gamma-ray activity". We also investigate an intriguing bright flare at VHE without a substantial flux increase in the X-rays. Within a leptonic scenario, this behaviour is best explained by the appearance of a second population of highly-energetic electrons spanning a narrow range of energies. Finally, our multi-wavelength correlation study also reveals an anti-correlation between the UV/optical and X-ray bands at a significance level above 3 sigma.

Published
2022

Catalog

Books, media, physical & digital resources
See catalog results