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97 results on '"Mirzaqulov D."'

1. Extragalactic fast X-ray transient from a weak relativistic jet associated with a Type Ic-BL supernova

Author

Sun, H., Li, W. -X., Liu, L. -D., Gao, H., Wang, X. -F., Yuan, W., Zhang, B., Filippenko, A. V., Xu, D., An, T., Ai, S., Brink, T. G., Liu, Y., Liu, Y. -Q., Wang, C. -Y., Wu, Q. -Y., Wu, X. -F., Yang, Y., Zhang, B. -B., Zheng, W. -K., Ahumada, T., Dai, Z. -G., Delaunay, J., Elias-Rosa, N., Benetti, S., Fu, S. -Y., Howell, D. A., Huang, Y. -F., Kasliwal, M. M., Karambelkar, V., Stein, R., Lei, W. -H., Lian, T. -Y., Peng, Z. -K., Ridnaia, A. V., Svinkin, D. S., Wang, X. -Y., Wang, A. -L., Wei, D. -M., An, J., Andrews, M., Bai, J. -M, Dai, C. -Y., Ehgamberdiev, S. A., Fan, Z., Farah, J., Feng, H. -C., Fynbo, J. P. U., Guo, W. -J., Guo, Z., Hu, M. -K., Hu, J. -W., Jiang, S. -Q., Jin, J. -J., Li, A., Li, J. -D., Li, R. -Z., Liang, Y. -F., Ling, Z. -X., Liu, X., Mao, J. -R., McCully, C., Mirzaqulov, D., Newsome, M., Gonzalez, E. Padilla, Pan, X., Terreran, G., Tinyanont, S., Wang, B. -T., Wang, L. -Z., Wen, X. -D., Xiang, D. -F., Xue, S. -J., Yang, J., Zhu, Z. -P., Cai, Z. -M., Castro-Tirado, A. J., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -H., Chen, Y. -F., Chen, Y., Cheng, H. -Q., Cordier, B., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Fan, D. -W., Feng, H., Guan, J., Han, D. -W., Hou, D. -J., Hu, H. -B., Huang, M. -H., Huo, J., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Kuulkers, E., Li, C. -K., Li, D. -Y., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Liu, C. -Z, Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Lu, F. -J., Luo, L. -D., Ma, J., Mao, X., Nandra, K., O'Brien, P., Pan, H. -W., Rau, A., Rea, N., Sanders, J., Song, L. -M., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, Y. -L., Wang, Y. -S., Xiong, D. -R., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, H. -N., Yang, X. -T., Yang, Y. -J., Zhang, C., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, Y. -L., Zhu, Y. -X., and Zhu, Z. -C.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Massive stars end their life as core-collapse supernovae, amongst which some extremes are Type Ic broad-lined supernovae associated with long-duration gamma-ray bursts (LGRBs) having powerful relativistic jets. Their less-extreme brethren make unsuccessful jets that are choked inside the stars, appearing as X-ray flashes or low-luminosity GRBs. On the other hand, there exists a population of extragalactic fast X-ray transients (EFXTs) with timescales ranging from seconds to thousands of seconds, whose origins remain obscure. Known sources that contribute to the observed EFXT population include the softer analogs of LGRBs, shock breakouts of supernovae, or unsuccessful jets. Here, we report the discovery of the bright X-ray transient EP240414a detected by the Einstein Probe (EP), which is associated with the Type Ic supernova SN 2024gsa at a redshift of 0.401. The X-ray emission evolution is characterised by a very soft energy spectrum peaking at < 1.3 keV, which makes it distinct from known LGRBs, X-ray flashes, or low-luminosity GRBs. Follow-up observations at optical and radio bands revealed the existence of a weak relativistic jet that interacts with an extended shell surrounding the progenitor star. Located on the outskirts of a massive galaxy, this event reveals a new population of explosions of Wolf-Rayet stars characterised by a less powerful engine that drives a successful but weak jet, possibly owing to a progenitor star with a smaller core angular momentum than in traditional LGRB progenitors., Comment: 43 pages, 9 figures, 4 tables, submitted. Comments are welcome

Published
2024

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

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

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

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

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

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

Published
2023

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

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

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

Published
2023
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5. The dual nature of blazar fast variability. Space and ground observations of S5 0716+714

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

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

Published
2020
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6. 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

7. SN 2018hti: a nearby superluminous supernova discovered in a metal-poor galaxy

Author

Lin, W. L., Wang, X. F., Li, W. X., Zhang, J. J., Mo, J., Sai, H. N., Zhang, X. H., Filippenko, A. V., Zheng, W. K., Brink, T. G., Baron, E., DerKacy, J. M., Ehgamberdiev, S. A., Mirzaqulov, D., Li, X., Zhang, J. C., Yan, S. Y., Xi, G. B., Hsiao, Y., Zhang, T. M., Wang, L. J., Liu, L. D., Xiang, D. F., Wu, C. Y., Rui, L. M., and Chen, Z. H.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

SN 2018hti is a Type I superluminous supernova (SLSN~I) with an absolute $g$-band magnitude of $-22.2$ at maximum brightness, discovered in a metal-poor galaxy at a redshift of 0.0612. We present extensive photometric and spectroscopic observations of this supernova, covering the phases from $\sim -35$ days to more than +340 days from the $r$-band maximum. Combining our $BVgri$-band photometry with {\it Swift} UVOT optical/ultraviolet photometry, we calculated the peak luminosity as $\sim 3.5\times10^{44}$ erg s$^{-1}$. Modeling the observed light curve reveals that the luminosity evolution of SN 2018hti can be produced by an ejecta mass of 5.8 $M_\odot$ and a magnetar with a magnetic field of $B=1.8\times10^{13}$~G having an initial spin period of $P_0=1.8$ ms. Based on such a magnetar-powered scenario and a larger sample, a correlation between the spin of the magnetar and the kinetic energy of the ejecta can be inferred for most SLSNe~I, suggesting a self-consistent scenario. Like for other SLSNe~I, the host galaxy of SN 2018hti is found to be relatively faint ($M_{g} = -17.75$ mag) and of low metallicity ($Z=0.3~Z_\odot$), with a star-formation rate of 0.3 $M_\odot$ yr$^{-1}$. According to simulation results of single-star evolution, SN 2018hti could originate from a massive, metal-poor star with a zero-age main sequence (ZAMS) mass of 25--40 $M_\odot$, or from a less massive rotating star with $M_\mathrm{ZAMS} \approx 16$--25 $M_\odot$. For the case of a binary system, its progenitor could also be a star with $M_\mathrm{ZAMS} \gtrsim 25$ $M_\odot$., Comment: 26 pages, 12 figures, 7 tables, published in MNRAS

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

Author

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

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

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

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

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

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

Published
2019
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10. The beamed jet and quasar core of the distant blazar 4C 71.07

Author

Raiteri, C. M., Villata, M., Carnerero, M. I., Acosta-Pulido, J. A., Mirzaqulov, D. O., Larionov, V. M., Romano, P., and Vercellone, S.

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

The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a two-year multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by ultraviolet and X-ray data from Swift, and by gamma-ray data by Fermi. The big blue bump is modelled by using optical and near-infrared mean spectra obtained during the campaign, together with optical and ultraviolet quasar templates. We give prescriptions to correct the source photometry in the various bands for the thermal contribution, in order to derive the non-thermal jet flux. The role of the intergalactic medium absorption is analysed in both the ultraviolet and X-ray bands. We provide opacity values to deabsorb ultraviolet data, and derive a best-guess value for the hydrogen column density through the analysis of X-ray spectra. We estimate the disc and jet bolometric luminosities, accretion rate, and black hole mass. Light curves do not show persistent correlations among flux changes at different frequencies. We study the polarimetric behaviour and find no correlation between polarisation degree and flux, even when correcting for the dilution effect of the big blue bump. Similarly, wide rotations of the electric vector polarisation angle do not seem to be connected with the source activity., Comment: 15 pages, 14 figures, in press for MNRAS

Published
2019
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11. AGILE, Fermi, Swift, and GASP-WEBT multi-wavelength observations of the high-redshift blazar 4C $+$71.07 in outburst

Author

Vercellone, S., Romano, P., Piano, G., Vittorini, V., Donnarumma, I., Munar-Adrover, P., Raiteri, C. M., Villata, M., Verrecchia, F., Lucarelli, F., Pittori, C., Bulgarelli, A., Fioretti, V., Tavani, M., Acosta-Pulido, J. A., Agudo, I., Arkharov, A. A., Bach, U., Bachev, R., Borman, G. A., Butuzova, M. S., Carnerero, M. I., Casadio, C., Damljanovic, G., D'Ammando, F., Di Paola, A., Doroshenko, V. T., Efimova, N. V., Ehgamberdiev, Sh. A., Giroletti, M., Gómez, J. L., Grishina, T. S., Järvelä, E., Klimanov, S. A., Kopatskaya, E. N., Kurtanidze, O. M., Lähteenmäki, A., Larionov, V. M., Larionova, L. V., Mihov, B., Mirzaqulov, D. O., Molina, S. N., Morozova, D. A., Nazarov, S. V., Orienti, M., Righini, S., Savchenko, S. S., Semkov, E., Slavcheva-Mihova, L., Strigachev, A., Tornikoski, M., Troitskaya, Yu. V., Vince, O., Cattaneo, P. W., Colafrancesco, S., Longo, F., Morselli, A., Paoletti, F., and Parmiggiani, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The flat-spectrum radio quasar 4C $+$71.07 is a high-redshift ($z=2.172$), $\gamma$-loud blazar whose optical emission is dominated by the thermal radiation from accretion disc. 4C $+$71.07 has been detected in outburst twice by the AGILE $\gamma$-ray satellite during the period end of October - mid November 2015, when it reached a $\gamma$-ray flux of the order of $F_{\rm E>100\,MeV} = (1.2 \pm 0.3)\times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$ and $F_{\rm E>100\,MeV} = (3.1 \pm 0.6)\times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$, respectively, allowing us to investigate the properties of the jet and of the emission region. We investigated its spectral energy distribution by means of almost simultaneous observations covering the cm, mm, near-infrared, optical, ultra-violet, X-ray and $\gamma$-ray energy bands obtained by the GASP-WEBT Consortium, the Swift and the AGILE and Fermi satellites. The spectral energy distribution of the second $\gamma$-ray flare (the one whose energy coverage is more dense) can be modelled by means of a one-zone leptonic model, yielding a total jet power of about $4\times10^{47}$ erg s$^{-1}$. During the most prominent $\gamma$-ray flaring period our model is consistent with a dissipation region within the broad-line region. Moreover, this class of high-redshift, large-mass black-hole flat-spectrum radio quasars might be good targets for future $\gamma$-ray satellites such as e-ASTROGAM., Comment: Accepted for publication in A&A. 9 pages, 4 Figures, 3 Tables

Published
2018
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12. 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
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13. The Bright $\gamma$-ray Flare of 3C 279 in June 2015: AGILE Detection and Multifrequency Follow-up Observations

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

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

Published
2018
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14. 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
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15. The awakening of BL Lacertae: observations by Fermi, Swift, and the GASP-WEBT

Author

Raiteri, C. M., Villata, M., D'Ammando, F., Larionov, V. M., Gurwell, M. A., Mirzaqulov, D. O., and Smith, P. S.

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

Since the launch of the Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) in collaboration with the Steward Observatory allows us to perform a detailed comparison with the daily gamma-ray observations by Fermi. Discrete correlation analysis between the optical and gamma-ray emission reveals correlation with a time lag of 0 +- 1 d, which suggests cospatiality of the corresponding jet emitting regions. A better definition of the time lag is hindered by the daily gaps in the sampling of the extremely fast flux variations. In general, optical flares present more structure and develop on longer time scales than corresponding gamma-ray flares. Observations at X-rays and at millimetre wavelengths reveal a common trend, which suggests that the region producing the mm and X-ray radiation is located downstream from the optical and gamma-ray-emitting zone in the jet. The mean optical degree of polarisation slightly decreases over the considered period and in general it is higher when the flux is lower. The optical electric vector polarisation angle (EVPA) shows a preferred orientation of about 15 deg, nearly aligned with the radio core EVPA and mean jet direction. Oscillations around it increase during the 2011-2012 outburst. We investigate the effects of a geometrical interpretation of the long-term flux variability on the polarisation. A helical magnetic field model predicts an evolution of the mean polarisation that is in reasonable agreement with the observations. These can be fully explained by introducing slight variations in the compression factor in a transverse shock waves model., Comment: 17 pages, 17 figures, 1 table, accepted for publication in MNRAS

Published
2013
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16. Variability of the blazar 4C 38.41 (B3 1633+382) from GHz frequencies to GeV energies

Author

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

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

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

Published
2012
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17. 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
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18. 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
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19. 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
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20. Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution

Author

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

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

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

Published
2020
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21. The dual nature of blazar fast variability: Space and ground observations of S5 0716+714

Author

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

Published
2020
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22. Multiwavelength Variability of BL Lacertae Measured with High Time Resolution

Author

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

Published
2020
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23. SN 2018hti: a nearby superluminous supernova discovered in a metal-poor galaxy

Author

Lin, W L, primary, Wang, X F, additional, Li, W X, additional, Zhang, J J, additional, Mo, J, additional, Sai, H N, additional, Zhang, X H, additional, Filippenko, A V, additional, Zheng, W K, additional, Brink, T G, additional, Baron, E, additional, DerKacy, J M, additional, Ehgamberdiev, S A, additional, Mirzaqulov, D, additional, Li, X, additional, Zhang, J C, additional, Yan, S Y, additional, Xi, G B, additional, Hsiao, Y, additional, Zhang, T M, additional, Wang, L J, additional, Liu, L D, additional, Xiang, D F, additional, Wu, C Y, additional, Rui, L M, additional, and Chen, Z H, additional

Published
2020
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24. Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio

Author

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

Published
2020
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25. The beamed jet and quasar core of the distant blazar 4C 71.07

Author

Raiteri, C M, primary, Villata, M, additional, Carnerero, M I, additional, Acosta-Pulido, J A, additional, Mirzaqulov, D O, additional, Larionov, V M, additional, Romano, P, additional, Vercellone, S, additional, Agudo, I, additional, Arkharov, A A, additional, Bach, U, additional, Bachev, R, additional, Baitieri, S, additional, Borman, G A, additional, Boschin, W, additional, Bozhilov, V, additional, Butuzova, M S, additional, Calcidese, P, additional, Carosati, D, additional, Casadio, C, additional, Chen, W-P, additional, Damljanovic, G, additional, Di Paola, A, additional, Doroshenko, V T, additional, Efimova, N V, additional, Ehgamberdiev, Sh A, additional, Giroletti, M, additional, Gómez, J L, additional, Grishina, T S, additional, Ibryamov, S, additional, Jermak, H, additional, Jorstad, S G, additional, Kimeridze, G N, additional, Klimanov, S A, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Kurtanidze, S O, additional, Lähteenmäki, A, additional, Larionova, E G, additional, Marscher, A P, additional, Mihov, B, additional, Minev, M, additional, Molina, S N, additional, Moody, J W, additional, Morozova, D A, additional, Nazarov, S V, additional, Nikiforova, A A, additional, Nikolashvili, M G, additional, Ovcharov, E, additional, Peneva, S, additional, Righini, S, additional, Rizzi, N, additional, Sadun, A C, additional, Samal, M R, additional, Savchenko, S S, additional, Semkov, E, additional, Sigua, L A, additional, Slavcheva-Mihova, L, additional, Steele, I A, additional, Strigachev, A, additional, Tornikoski, M, additional, Troitskaya, Yu V, additional, Troitsky, I S, additional, and Vince, O, additional

Published
2019
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26. AGILE, Fermi, Swift, and GASP/WEBT multi-wavelength observations of the high-redshift blazar 4C +71.07 in outburst

Author

Vercellone, S., primary, Romano, P., additional, Piano, G., additional, Vittorini, V., additional, Donnarumma, I., additional, Munar-Adrover, P., additional, Raiteri, C. M., additional, Villata, M., additional, Verrecchia, F., additional, Lucarelli, F., additional, Pittori, C., additional, Bulgarelli, A., additional, Fioretti, V., additional, Tavani, M., additional, Acosta-Pulido, J. A., additional, Agudo, I., additional, Arkharov, A. A., additional, Bach, U., additional, Bachev, R., additional, Borman, G. A., additional, Butuzova, M. S., additional, Carnerero, M. I., additional, Casadio, C., additional, Damljanovic, G., additional, D’Ammando, F., additional, Di Paola, A., additional, Doroshenko, V. T., additional, Efimova, N. V., additional, Ehgamberdiev, Sh. A., additional, Giroletti, M., additional, Gómez, J. L., additional, Grishina, T. S., additional, Järvelä, E., additional, Klimanov, S. A., additional, Kopatskaya, E. N., additional, Kurtanidze, O. M., additional, Lähteenmäki, A., additional, Larionov, V. M., additional, Larionova, L. V., additional, Mihov, B., additional, Mirzaqulov, D. O., additional, Molina, S. N., additional, Morozova, D. A., additional, Nazarov, S. V., additional, Orienti, M., additional, Righini, S., additional, Savchenko, S. S., additional, Semkov, E., additional, Slavcheva-Mihova, L., additional, Strigachev, A., additional, Tornikoski, M., additional, Troitskaya, Yu. V., additional, Vince, O., additional, Cattaneo, P. W., additional, Colafrancesco, S., additional, Longo, F., additional, Morselli, A., additional, Paoletti, F., additional, and Parmiggiani, N., additional

Published
2019
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27. The dual nature of blazar fast variability: Space and ground observations of S5 0716+714.

Author

Raiteri, C M, Villata, M, Carosati, D, Benítez, E, Kurtanidze, S O, Gupta, A C, Mirzaqulov, D O, D'Ammando, F, Larionov, V M, Pursimo, T, Acosta-Pulido, J A, Baida, G V, Balmaverde, B, Bonnoli, G, Borman, G A, Carnerero, M I, Chen, W-P, Dhiman, V, Di Maggio, A, and Ehgamberdiev, S A

Subjects
BL Lacertae objects, TIME series analysis, SPACE telescopes, CUBIC curves
Abstract

Blazar S5 0716+714 is well-known for its short-term variability, down to intraday time-scales. We here present the 2-min cadence optical light curve obtained by the TESS space telescope in 2019 December–2020 January and analyse the object fast variability with unprecedented sampling. Supporting observations by the Whole Earth Blazar Telescope Collaboration in B, V, R , and I bands allow us to investigate the spectral variability during the TESS pointing. The spectral analysis is further extended in frequency to the UV and X-ray bands with data from the Neil Gehrels Swift Observatory. We develop a new method to unveil the shortest optical variability time-scales. This is based on progressive de-trending of the TESS light curve by means of cubic spline interpolations through the binned fluxes, with decreasing time bins. The de-trended light curves are then analysed with classical tools for time-series analysis (periodogram, autocorrelation, and structure functions). The results show that below 3 d there are significant characteristic variability time-scales of about 1.7, 0.5, and 0.2 d. Variability on time-scales |$\lesssim 0.2$|  d is strongly chromatic and must be ascribed to intrinsic energetic processes involving emitting regions, likely jet substructures, with dimension less than about 10−3 pc. In contrast, flux changes on time-scales |$\gtrsim 0.5$|  d are quasi-achromatic and are probably due to Doppler factor changes of geometric origin. [ABSTRACT FROM AUTHOR]

Published
2021
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28. Blazar spectral variability as explained by a twisted inhomogeneous jet

Author

Raiteri C., Villata M., Acosta-Pulido J., Agudo I., Arkharov A., Bachev R., Baida G., Benítez E., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carnerero M., Carosati D., Casadio C., Castro-Segura N., Chen W., Damljanovic G., D'Ammando F., Di Paola A., Echevarría J., Efimova N., Ehgamberdiev S., Espinosa C., Fuentes A., Giunta A., Gómez J., Grishina T., Gurwell M., Hiriart D., Jermak H., Jordan B., Jorstad S., Joshi M., Kopatskaya E., Kuratov K., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionov V., Larionova E., Larionova L., Lázaro C., Lin C., Malmrose M., Marscher A., Matsumoto K., McBreen B., Michel R., Mihov B., Minev M., Mirzaqulov D., Mokrushina A., Molina S., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Okhmat D., Ovcharov E., Pinna F., Polakis T., Protasio C., Pursimo T., Redondo-Lorenzo F., Rizzi N., Rodriguez-Coira G., Sadakane K., Sadun A., Samal M., Savchenko S., Semkov E., Skiff B., Slavcheva-Mihova L., Smith P., and Steele I.

Subjects
Astrophysics::High Energy Astrophysical Phenomena
Abstract

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions - such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution - can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016-2017 (brightness increase of six magnitudes) occurred when the corresponding emitting region had a small viewing angle. The agreement between observations and theoretical predictions can be seen as further validation of the relativistic beaming theory.

Published
2017

29. The Brightγ-ray Flare of 3C 279 in 2015 June:AGILEDetection and Multifrequency Follow-up Observations

Author

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

Published
2018
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30. The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission

Author

Raiteri, C. M., Stamerra, A., Villata, M., Larionov, V. M., Acosta-Pulido, J. A., Arévalo, M. J., Arkharov, A. A., Bachev, R., Benítez, E., Bozhilov, V. V., Borman, G. A., Buemi, C. S., Calcidese, P., Carnerero, M. I., Carosati, D., Chigladze, R. A., Damljanovic, G., Di Paola, A., Doroshenko, V. T., Efimova, N. V., Ehgamberdiev, Sh. A., Giroletti, M., González-Morales, P. A., Grinon-Marin, A. B., Grishina, T. S., Hiriart, D., Ibryamov, S., Klimanov, S. A., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Kurtenkov, A. A., Larionova, L. V., Larionova, E. G., Lázaro, C., Lähteenmäki, A., Leto, P., Markovic, G., Mirzaqulov, D. O., Mokrushina, A. A., Morozova, D. A., Mújica, R., Nazarov, S. V., Nikolashvili, M. G., Ohlert, J. M., Ovcharov, E. P., Paiano, S., Pastor Yabar, A., Prandini, E., Ramakrishnan, V., Sadun, A. C., Semkov, E., Sigua, L. A., Strigachev, A., Tammi, J., Tornikoski, M., Trigilio, C., Troitskaya, Yu. V., Troitsky, I. S., Umana, G., Velasco, S., Vince, O., Raiteri, C. M., Stamerra, A., Villata, M., Larionov, V. M., Acosta-Pulido, J. A., Arévalo, M. J., Arkharov, A. A., Bachev, R., Benítez, E., Bozhilov, V. V., Borman, G. A., Buemi, C. S., Calcidese, P., Carnerero, M. I., Carosati, D., Chigladze, R. A., Damljanovic, G., Di Paola, A., Doroshenko, V. T., Efimova, N. V., Ehgamberdiev, Sh. A., Giroletti, M., González-Morales, P. A., Grinon-Marin, A. B., Grishina, T. S., Hiriart, D., Ibryamov, S., Klimanov, S. A., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Kurtenkov, A. A., Larionova, L. V., Larionova, E. G., Lázaro, C., Lähteenmäki, A., Leto, P., Markovic, G., Mirzaqulov, D. O., Mokrushina, A. A., Morozova, D. A., Mújica, R., Nazarov, S. V., Nikolashvili, M. G., Ohlert, J. M., Ovcharov, E. P., Paiano, S., Pastor Yabar, A., Prandini, E., Ramakrishnan, V., Sadun, A. C., Semkov, E., Sigua, L. A., Strigachev, A., Tammi, J., Tornikoski, M., Trigilio, C., Troitskaya, Yu. V., Troitsky, I. S., Umana, G., Velasco, S., and Vince, O.

Abstract

A multifrequency campaign on the BL Lac object PG 1553+113 was organized by the Whole Earth Blazar Telescope (WEBT) in 2013 April-August, involving 19 optical, two near-IR, and three radio telescopes. The aim was to study the source behaviour at low energies during and around the high-energy observations by the Major Atmospheric Gamma-ray Imaging Cherenkov telescopes in April-July. We also analyse the UV and X-ray data acquired by the Swift and XMM-Newton satellites in the same period. The WEBT and satellite observations allow us to detail the synchrotron emission bump in the source spectral energy distribution (SED). In the optical, we found a general bluer-when-brighter trend. The X-ray spectrum remained stable during 2013, but a comparison with previous observations suggests that it becomes harder when the X-ray flux increases. The long XMM-Newton exposure reveals a curved X-ray spectrum. In the SED, the XMM-Newton data show a hard near-UV spectrum, while Swift data display a softer shape that is confirmed by previous Hubble Space Telescope/Cosmic Origins Spectrograph and International Ultraviolet Explorer observations. Polynomial fits to the optical-X-ray SED show that the synchrotron peak likely lies in the 4-30eV energy range, with a general shift towards higher frequencies for increasing X-ray brightness. However, the UV and X-ray spectra do not connect smoothly. Possible interpretations include: (i) orientation effects, (ii) additional absorption, (iii) multiple emission components, and (iv) a peculiar energy distribution of relativistic electrons. We discuss the first possibility in terms of an inhomogeneous helical jet model

Published
2017

31. Synchrotron emission from the blazar PG 1553+113. An analysis of its flux and polarization variability

Author

Raiteri, C. M., primary, Nicastro, F., additional, Stamerra, A., additional, Villata, M., additional, Larionov, V. M., additional, Blinov, D., additional, Acosta-Pulido, J. A., additional, Arévalo, M. J., additional, Arkharov, A. A., additional, Bachev, R., additional, Borman, G. A., additional, Carnerero, M. I., additional, Carosati, D., additional, Cecconi, M., additional, Chen, W.-P., additional, Damljanovic, G., additional, Di Paola, A., additional, Ehgamberdiev, Sh. A., additional, Frasca, A., additional, Giroletti, M., additional, González-Morales, P. A., additional, Griñon-Marín, A. B., additional, Grishina, T. S., additional, Huang, P.-C., additional, Ibryamov, S., additional, Klimanov, S. A., additional, Kopatskaya, E. N., additional, Kurtanidze, O. M., additional, Kurtanidze, S. O., additional, Lähteenmäki, A., additional, Larionova, E. G., additional, Larionova, L. V., additional, Lázaro, C., additional, Leto, G., additional, Liodakis, I., additional, Martínez-Lombilla, C., additional, Mihov, B., additional, Mirzaqulov, D. O., additional, Mokrushina, A. A., additional, Moody, J. W., additional, Morozova, D. A., additional, Nazarov, S. V., additional, Nikolashvili, M. G., additional, Ohlert, J. M., additional, Panopoulou, G. V., additional, Pastor Yabar, A., additional, Pinna, F., additional, Protasio, C., additional, Rizzi, N., additional, Sadun, A. C., additional, Savchenko, S. S., additional, Semkov, E., additional, Sigua, L. A., additional, Slavcheva-Mihova, L., additional, Strigachev, A., additional, Tornikoski, M., additional, Troitskaya, Yu. V., additional, Troitsky, I. S., additional, Vasilyev, A. A., additional, Vera, R. J. C., additional, Vince, O., additional, and Zanmar Sanchez, R., additional

Published
2016
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32. Exceptional outburst of the blazar CTA 102 in 2012: the GASP–WEBT campaign and its extension

Author

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

Published
2016
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33. The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission

Author

Raiteri, C. M., primary, Stamerra, A., additional, Villata, M., additional, Larionov, V. M., additional, Acosta-Pulido, J. A., additional, Arévalo, M. J., additional, Arkharov, A. A., additional, Bachev, R., additional, Benítez, E., additional, Bozhilov, V. V., additional, Borman, G. A., additional, Buemi, C. S., additional, Calcidese, P., additional, Carnerero, M. I., additional, Carosati, D., additional, Chigladze, R. A., additional, Damljanovic, G., additional, Di Paola, A., additional, Doroshenko, V. T., additional, Efimova, N. V., additional, Ehgamberdiev, Sh. A., additional, Giroletti, M., additional, González-Morales, P. A., additional, Grinon-Marin, A. B., additional, Grishina, T. S., additional, Hiriart, D., additional, Ibryamov, S., additional, Klimanov, S. A., additional, Kopatskaya, E. N., additional, Kurtanidze, O. M., additional, Kurtanidze, S. O., additional, Kurtenkov, A. A., additional, Larionova, L. V., additional, Larionova, E. G., additional, Lázaro, C., additional, Lähteenmäki, A., additional, Leto, P., additional, Markovic, G., additional, Mirzaqulov, D. O., additional, Mokrushina, A. A., additional, Morozova, D. A., additional, Mújica, R., additional, Nazarov, S. V., additional, Nikolashvili, M. G., additional, Ohlert, J. M., additional, Ovcharov, E. P., additional, Paiano, S., additional, Pastor Yabar, A., additional, Prandini, E., additional, Ramakrishnan, V., additional, Sadun, A. C., additional, Semkov, E., additional, Sigua, L. A., additional, Strigachev, A., additional, Tammi, J., additional, Tornikoski, M., additional, Trigilio, C., additional, Troitskaya, Yu. V., additional, Troitsky, I. S., additional, Umana, G., additional, Velasco, S., additional, and Vince, O., additional

Published
2015
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34. Multiwavelength behaviour of the blazar OJ 248 from radio to γ-rays★

Author

Carnerero, M. I., primary, Raiteri, C. M., additional, Villata, M., additional, Acosta-Pulido, J. A., additional, D'Ammando, F., additional, Smith, P. S., additional, Larionov, V. M., additional, Agudo, I., additional, Arévalo, M. J., additional, Arkharov, A. A., additional, Bach, U., additional, Bachev, R., additional, Benítez, E., additional, Blinov, D. A., additional, Bozhilov, V., additional, Buemi, C. S., additional, Bueno Bueno, A., additional, Carosati, D., additional, Casadio, C., additional, Chen, W. P., additional, Damljanovic, G., additional, Paola, A. Di, additional, Efimova, N. V., additional, Ehgamberdiev, Sh. A., additional, Giroletti, M., additional, Gómez, J. L., additional, González-Morales, P. A., additional, Grinon-Marin, A. B., additional, Grishina, T. S., additional, Gurwell, M. A., additional, Hiriart, D., additional, Hsiao, H. Y., additional, Ibryamov, S., additional, Jorstad, S. G., additional, Joshi, M., additional, Kopatskaya, E. N., additional, Kurtanidze, O. M., additional, Kurtanidze, S. O., additional, Lähteenmäki, A., additional, Larionova, E. G., additional, Larionova, L. V., additional, Lázaro, C., additional, Leto, P., additional, Lin, C. S., additional, Lin, H. C., additional, Manilla-Robles, A. I., additional, Marscher, A. P., additional, McHardy, I. M., additional, Metodieva, Y., additional, Mirzaqulov, D. O., additional, Mokrushina, A. A., additional, Molina, S. N., additional, Morozova, D. A., additional, Nikolashvili, M. G., additional, Orienti, M., additional, Ovcharov, E., additional, Panwar, N., additional, Pastor Yabar, A., additional, Puerto Giménez, I., additional, Ramakrishnan, V., additional, Richter, G. M., additional, Rossini, M., additional, Sigua, L. A., additional, Strigachev, A., additional, Taylor, B., additional, Tornikoski, M., additional, Trigilio, C., additional, Troitskaya, Yu. V., additional, Troitsky, I. S., additional, Umana, G., additional, Valcheva, A., additional, Velasco, S., additional, Vince, O., additional, Wehrle, A. E., additional, and Wiesemeyer, H., additional

Published
2015
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35. The awakening of BL Lacertae: observations by Fermi, Swift and the GASP-WEBT★

Author

Raiteri, C. M., primary, Villata, M., additional, D'Ammando, F., additional, Larionov, V. M., additional, Gurwell, M. A., additional, Mirzaqulov, D. O., additional, Smith, P. S., additional, Acosta-Pulido, J. A., additional, Agudo, I., additional, Arévalo, M. J., additional, Bachev, R., additional, Benítez, E., additional, Berdyugin, A., additional, Blinov, D. A., additional, Borman, G. A., additional, Böttcher, M., additional, Bozhilov, V., additional, Carnerero, M. I., additional, Carosati, D., additional, Casadio, C., additional, Chen, W. P., additional, Doroshenko, V. T., additional, Efimov, Yu. S., additional, Efimova, N. V., additional, Ehgamberdiev, Sh. A., additional, Gómez, J. L., additional, González-Morales, P. A., additional, Hiriart, D., additional, Ibryamov, S., additional, Jadhav, Y., additional, Jorstad, S. G., additional, Joshi, M., additional, Kadenius, V., additional, Klimanov, S. A., additional, Kohli, M., additional, Konstantinova, T. S., additional, Kopatskaya, E. N., additional, Koptelova, E., additional, Kimeridze, G., additional, Kurtanidze, O. M., additional, Larionova, E. G., additional, Larionova, L. V., additional, Ligustri, R., additional, Lindfors, E., additional, Marscher, A. P., additional, McBreen, B., additional, McHardy, I. M., additional, Metodieva, Y., additional, Molina, S. N., additional, Morozova, D. A., additional, Nazarov, S. V., additional, Nikolashvili, M. G., additional, Nilsson, K., additional, Okhmat, D. N., additional, Ovcharov, E., additional, Panwar, N., additional, Pasanen, M., additional, Peneva, S., additional, Phipps, J., additional, Pulatova, N. G., additional, Reinthal, R., additional, Ros, J. A., additional, Sadun, A. C., additional, Schwartz, R. D., additional, Semkov, E., additional, Sergeev, S. G., additional, Sigua, L. A., additional, Sillanpää, A., additional, Smith, N., additional, Stoyanov, K., additional, Strigachev, A., additional, Takalo, L. O., additional, Taylor, B., additional, Thum, C., additional, Troitsky, I. S., additional, Valcheva, A., additional, Wehrle, A. E., additional, and Wiesemeyer, H., additional

Published
2013
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36. Variability of the blazar 4C 38.41 (B3 1633+382) from GHz frequencies to GeV energies

Author

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

Published
2012
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40. LIGO/Virgo S190814bv: CFHTphotometryof AT2019npv

Author

Wang, X., Antier, S., Coughlin, M., Li, W., Zhang, X., Mo, J., Xi, G., Bai, J., Basa, S., Bertin, E., Blazek, M., Michel Boer, Coleiro, A., Christensen, N., Ehgamberdiev, S., Kann, D. A., Klotz, A., David Coward, Corre, D., Ducoin, J. G., Bruce Gendre, Hello, P., Hu, L., Lachaud, C., Jiang, X., Leroy, N., Li, B., Lin, W., Mirzaqulov, D., Sun, T., Thoene, C., Turpin, D., Wang, L., Ugarte Postigo, A., Wu, X., Zhao, H., Zeng, X., Zhang, J. J., Zhang, J. C., Aogot Collaboration, and Grandma Collaboration

41. The beamed jet and quasar core of the distant blazar 4C 71.07

Author

Raiteri C., Villata M., Carnerero M., Acosta-Pulido J., Mirzaqulov D., Larionov V., Romano P., Vercellone S., Agudo I., Arkharov A., Bach U., Bachev R., Baitieri S., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Ibryamov S., Jermak H., Jorstad S., Kimeridze G., Klimanov S., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Marscher A., Mihov B., Minev M., Molina S., Moody J., Morozova D., Nazarov S., Nikiforova A., Nikolashvili M., Ovcharov E., Peneva S., Righini S., Rizzi N., Sadun A., Samal M., Savchenko S., Semkov E., Sigua L., Slavcheva-Mihova L., Steele I., Strigachev A., Tornikoski M., Troitskaya Y., Troitsky I., Vince O., Raiteri C., Villata M., Carnerero M., Acosta-Pulido J., Mirzaqulov D., Larionov V., Romano P., Vercellone S., Agudo I., Arkharov A., Bach U., Bachev R., Baitieri S., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Ibryamov S., Jermak H., Jorstad S., Kimeridze G., Klimanov S., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Marscher A., Mihov B., Minev M., Molina S., Moody J., Morozova D., Nazarov S., Nikiforova A., Nikolashvili M., Ovcharov E., Peneva S., Righini S., Rizzi N., Sadun A., Samal M., Savchenko S., Semkov E., Sigua L., Slavcheva-Mihova L., Steele I., Strigachev A., Tornikoski M., Troitskaya Y., Troitsky I., and Vince O.

Abstract

© 2019 The Author(s). The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a 2- yr multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by ultraviolet and X-ray data from Swift, and by γ-ray data by Fermi. The big blue bump is modelled by using optical and near-infrared mean spectra obtained during the campaign, together with optical and ultraviolet quasar templates. We give prescriptions to correct the source photometry in the various bands for the thermal contribution, in order to derive the non-thermal jet flux. The role of the intergalactic medium absorption is analysed in both the ultraviolet and X-ray bands.We provide opacity values to deabsorb ultraviolet data, and derive a best-guess value for the hydrogen column density of Nbest H = 6.3 × 1020 cm-2through the analysis of X-ray spectra.We estimate the disc and jet bolometric luminosities, accretion rate, and black hole mass. Light curves do not show persistent correlations among flux changes at different frequencies. We study the polarimetric behaviour and find no correlation between polarization degree and flux, even when correcting for the dilution effect of the big blue bump. Similarly, wide rotations of the electric vector polarization angle do not seem to be connected with the source activity.

42. AGILE, Fermi, Swift, and GASP/WEBT multi-wavelength observations of the high-redshift blazar 4C +71.07 in outburst

Author

Vercellone S., Romano P., Piano G., Vittorini V., Donnarumma I., Munar-Adrover P., Raiteri C., Villata M., Verrecchia F., Lucarelli F., Pittori C., Bulgarelli A., Fioretti V., Tavani M., Acosta-Pulido J., Agudo I., Arkharov A., Bach U., Bachev R., Borman G., Butuzova M., Carnerero M., Casadio C., Damljanovic G., D'Ammando F., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Järvelä E., Klimanov S., Kopatskaya E., Kurtanidze O., Lähteenmäki A., Larionov V., Larionova L., Mihov B., Mirzaqulov D., Molina S., Morozova D., Nazarov S., Orienti M., Righini S., Savchenko S., Semkov E., Slavcheva-Mihova L., Strigachev A., Tornikoski M., Troitskaya Y., Vince O., Cattaneo P., Colafrancesco S., Longo F., Morselli A., Paoletti F., Parmiggiani N., Vercellone S., Romano P., Piano G., Vittorini V., Donnarumma I., Munar-Adrover P., Raiteri C., Villata M., Verrecchia F., Lucarelli F., Pittori C., Bulgarelli A., Fioretti V., Tavani M., Acosta-Pulido J., Agudo I., Arkharov A., Bach U., Bachev R., Borman G., Butuzova M., Carnerero M., Casadio C., Damljanovic G., D'Ammando F., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Järvelä E., Klimanov S., Kopatskaya E., Kurtanidze O., Lähteenmäki A., Larionov V., Larionova L., Mihov B., Mirzaqulov D., Molina S., Morozova D., Nazarov S., Orienti M., Righini S., Savchenko S., Semkov E., Slavcheva-Mihova L., Strigachev A., Tornikoski M., Troitskaya Y., Vince O., Cattaneo P., Colafrancesco S., Longo F., Morselli A., Paoletti F., and Parmiggiani N.

Abstract

© ESO 2019. Context. The flat-spectrum radio quasar 4C +71.07 is a high-redshift (z = 2.172), γ-loud blazar whose optical emission is dominated by thermal radiation from the accretion disc. Aims. 4C +71.07 has been detected in outburst twice by the AGILE γ-ray satellite during the period from the end of October to mid-November 2015, when it reached a γ-ray flux of the order of F(E > 100 MeV)=(1.2 ± 0.3)×10 -6 photons cm -2 s -1 and F(E > 100 MeV)=(3.1 ± 0.6)×10 -6 photons cm -2 s -1 , respectively, allowing us to investigate the properties of the jet and the emission region. Methods. We investigated its spectral energy distribution by means of almost-simultaneous observations covering the cm, mm, near-infrared, optical, ultraviolet, X-ray, and γ-ray energy bands obtained by the GASP-WEBT Consortium and the Swift, AGILE, and Fermi satellites. Results. The spectral energy distribution of the second γ-ray flare (whose energy coverage is more dense) can be modelled by means of a one-zone leptonic model, yielding a total jet power of about 4 × 10 47 erg s -1 . Conclusions. During the most prominent γ-ray flaring period our model is consistent with a dissipation region within the broad-line region. Moreover, this class of high-redshift, flat-spectrum radio quasars with high-mass black holes might be good targets for future γ-ray satellites such as e-ASTROGAM.

43. The Bright γ-ray Flare of 3C 279 in 2015 June: AGILE Detection and Multifrequency Follow-up Observations

Author

Chen W., Ehgamberdiev S., Goded A., Grishina T., Hiriart D., Hsiao H., Jorstad S., Kimeridze G., Kopatskaya E., Kurtanidze O., Kurtanidze S., Larionov V., Larionova L., Marscher A., Mirzaqulov D., Morozova D., Nilsson K., Samal M., Sigua L., Spassov B., Strigachev A., Takalo L., Antonelli L., Bulgarelli A., Cattaneo P., Colafrancesco S., Giommi P., Longo F., Morselli A., Paoletti F., Chen W., Ehgamberdiev S., Goded A., Grishina T., Hiriart D., Hsiao H., Jorstad S., Kimeridze G., Kopatskaya E., Kurtanidze O., Kurtanidze S., Larionov V., Larionova L., Marscher A., Mirzaqulov D., Morozova D., Nilsson K., Samal M., Sigua L., Spassov B., Strigachev A., Takalo L., Antonelli L., Bulgarelli A., Cattaneo P., Colafrancesco S., Giommi P., Longo F., Morselli A., and Paoletti F.

Abstract

© 2018. The American Astronomical Society. All rights reserved.. We report the AGILE detection and the results of the multifrequency follow-up observations of a bright γ-ray flare of the blazar 3C 279 in 2015 June. We use AGILE and Fermi gamma-ray data, together with Swift X-ray andoptical-ultraviolet data, and ground-based GASP-WEBT optical observations, including polarization information, to study the source variability and the overall spectral energy distribution during the γ-ray flare. The γ-ray flaring data, compared with as yet unpublished simultaneous optical data that will allow constraints on the big blue bump disk luminosity, show very high Compton dominance values of ∼100, with the ratio of γ-ray to optical emission rising by a factor of three in a few hours. The multiwavelength behavior of the source during the flare challenges one-zone leptonic theoretical models. The new observations during the 2015 June flare are also compared with already published data and nonsimultaneous historical 3C 279 archival data.

44. Multiwavelength behaviour of the blazar OJ 248 from radio to γ -rays

Author

Carnerero M., Raiteri C., Villata M., Acosta-Pulido J., D'Ammando F., Smith P., Larionov V., Agudo I., Arévalo M., Arkharov A., Bach U., Bachev R., Benítez E., Blinov D., Bozhilov V., Buemi C., Bueno Bueno A., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., González-Morales P., Grinon-Marin A., Grishina T., Gurwell M., Hiriart D., Hsiao H., Ibryamov S., Jorstad S., Joshi M., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto P., Lin C., Lin H., Manilla-Robles A., Marscher A., McHardy I., Metodieva Y., Mirzaqulov D., Mokrushina A., Molina S., Morozova D., Nikolashvili M., Orienti M., Ovcharov E., Panwar N., Pastor Yabar A., Puerto Giménez I., Ramakrishnan V., Richter G., Rossini M., Sigua L., Strigachev A., Taylor B., Tornikoski M., Trigilio C., Troitskaya Y., Troitsky I., Umana G., Valcheva A., Velasco S., Vince O., Wehrle A., Wiesemeyer H., Carnerero M., Raiteri C., Villata M., Acosta-Pulido J., D'Ammando F., Smith P., Larionov V., Agudo I., Arévalo M., Arkharov A., Bach U., Bachev R., Benítez E., Blinov D., Bozhilov V., Buemi C., Bueno Bueno A., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., González-Morales P., Grinon-Marin A., Grishina T., Gurwell M., Hiriart D., Hsiao H., Ibryamov S., Jorstad S., Joshi M., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto P., Lin C., Lin H., Manilla-Robles A., Marscher A., McHardy I., Metodieva Y., Mirzaqulov D., Mokrushina A., Molina S., Morozova D., Nikolashvili M., Orienti M., Ovcharov E., Panwar N., Pastor Yabar A., Puerto Giménez I., Ramakrishnan V., Richter G., Rossini M., Sigua L., Strigachev A., Taylor B., Tornikoski M., Trigilio C., Troitskaya Y., Troitsky I., Umana G., Valcheva A., Velasco S., Vince O., Wehrle A., and Wiesemeyer H.

Abstract

© 2015 The Authors. We present an analysis of the multiwavelength behaviour of the blazar OJ 248 at z = 0.939 in the period 2006-2013. We use low-energy data (optical, near-infrared, and radio) obtained by 21 observatories participating in the Gamma-Ray Large Area Space Telescope (GLAST)-AGILE Support Program of the Whole Earth Blazar Telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi (γ -rays) satellites, to study flux and spectral variability and correlations among emissions in different bands. We take into account the effect of absorption by the Damped Lyman α intervening system at z = 0.525. Two major outbursts were observed in 2006-2007 and in 2012-2013 at optical and near-IR wavelengths, while in the high-frequency radio light curves prominent radio outbursts are visible peaking at the end of 2010 and beginning of 2013, revealing a complex radio-optical correlation. Crosscorrelation analysis suggests a delay of the optical variations after the γ -ray ones of about a month, which is a peculiar behaviour in blazars. We also analyse optical polarimetric and spectroscopic data. The average polarization percentage P is less than 3 per cent, but it reaches~19 per cent during the early stage of the 2012-2013 outburst.Avague correlation of P with brightness is observed. There is no preferred electric vector polarization angle and during the outburst the linear polarization vector shows wide rotations in both directions, suggesting a complex behaviour/structure of the jet and possible turbulence. The analysis of 140 optical spectra acquired at the Steward Observatory reveals a strong Mg II broad emission line with an essentially stable flux of 6.2 × 10-15 erg cm-2 s-1 and a full width at half-maximum of 2053 km s-1.

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

Author

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

Abstract

Context. After years of modest optical activity, the quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum, renewing interest in this source. Aims. We present the results of low-energy multifrequency monitoring by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (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. This combined study aims to provide insights into the source broad-band emission and variability properties. Methods. We assemble optical, near-infrared, millimetre, and radio light curves and investigate their features and correlations. In the optical, we also analyse the spectroscopic and polarimetric properties of the source. We then compare the low-energy emission behaviour with that at high energies. Results. In the optical-UV band, several results indicate that there is a contribution from a quasi-stellar-object (QSO) like emission component, in addition to both variable and polarised jet emission. In the optical, the source is redder-when-brighter, at least for R a3; 16. The optical spectra display broad emission lines, whose flux is constant in time. The observed degree of polarisation increases with flux and is higher in the red than the blue. The spectral energy distribution reveals a bump peaking around the U band. 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 γ-ray flux apparently fades in time, likely because of an increasing optical to γ-ray flux ratio. Conclusions. As suggested fo

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

Author

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

Abstract

Context. After years of modest optical activity, the quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum, renewing interest in this source. Aims. We present the results of low-energy multifrequency monitoring by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (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. This combined study aims to provide insights into the source broad-band emission and variability properties. Methods. We assemble optical, near-infrared, millimetre, and radio light curves and investigate their features and correlations. In the optical, we also analyse the spectroscopic and polarimetric properties of the source. We then compare the low-energy emission behaviour with that at high energies. Results. In the optical-UV band, several results indicate that there is a contribution from a quasi-stellar-object (QSO) like emission component, in addition to both variable and polarised jet emission. In the optical, the source is redder-when-brighter, at least for R a3; 16. The optical spectra display broad emission lines, whose flux is constant in time. The observed degree of polarisation increases with flux and is higher in the red than the blue. The spectral energy distribution reveals a bump peaking around the U band. 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 γ-ray flux apparently fades in time, likely because of an increasing optical to γ-ray flux ratio. Conclusions. As suggested fo

47. Multiwavelength behaviour of the blazar OJ 248 from radio to γ -rays

Author

Carnerero M., Raiteri C., Villata M., Acosta-Pulido J., D'Ammando F., Smith P., Larionov V., Agudo I., Arévalo M., Arkharov A., Bach U., Bachev R., Benítez E., Blinov D., Bozhilov V., Buemi C., Bueno Bueno A., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., González-Morales P., Grinon-Marin A., Grishina T., Gurwell M., Hiriart D., Hsiao H., Ibryamov S., Jorstad S., Joshi M., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto P., Lin C., Lin H., Manilla-Robles A., Marscher A., McHardy I., Metodieva Y., Mirzaqulov D., Mokrushina A., Molina S., Morozova D., Nikolashvili M., Orienti M., Ovcharov E., Panwar N., Pastor Yabar A., Puerto Giménez I., Ramakrishnan V., Richter G., Rossini M., Sigua L., Strigachev A., Taylor B., Tornikoski M., Trigilio C., Troitskaya Y., Troitsky I., Umana G., Valcheva A., Velasco S., Vince O., Wehrle A., Wiesemeyer H., Carnerero M., Raiteri C., Villata M., Acosta-Pulido J., D'Ammando F., Smith P., Larionov V., Agudo I., Arévalo M., Arkharov A., Bach U., Bachev R., Benítez E., Blinov D., Bozhilov V., Buemi C., Bueno Bueno A., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., González-Morales P., Grinon-Marin A., Grishina T., Gurwell M., Hiriart D., Hsiao H., Ibryamov S., Jorstad S., Joshi M., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto P., Lin C., Lin H., Manilla-Robles A., Marscher A., McHardy I., Metodieva Y., Mirzaqulov D., Mokrushina A., Molina S., Morozova D., Nikolashvili M., Orienti M., Ovcharov E., Panwar N., Pastor Yabar A., Puerto Giménez I., Ramakrishnan V., Richter G., Rossini M., Sigua L., Strigachev A., Taylor B., Tornikoski M., Trigilio C., Troitskaya Y., Troitsky I., Umana G., Valcheva A., Velasco S., Vince O., Wehrle A., and Wiesemeyer H.

Abstract

© 2015 The Authors. We present an analysis of the multiwavelength behaviour of the blazar OJ 248 at z = 0.939 in the period 2006-2013. We use low-energy data (optical, near-infrared, and radio) obtained by 21 observatories participating in the Gamma-Ray Large Area Space Telescope (GLAST)-AGILE Support Program of the Whole Earth Blazar Telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi (γ -rays) satellites, to study flux and spectral variability and correlations among emissions in different bands. We take into account the effect of absorption by the Damped Lyman α intervening system at z = 0.525. Two major outbursts were observed in 2006-2007 and in 2012-2013 at optical and near-IR wavelengths, while in the high-frequency radio light curves prominent radio outbursts are visible peaking at the end of 2010 and beginning of 2013, revealing a complex radio-optical correlation. Crosscorrelation analysis suggests a delay of the optical variations after the γ -ray ones of about a month, which is a peculiar behaviour in blazars. We also analyse optical polarimetric and spectroscopic data. The average polarization percentage P is less than 3 per cent, but it reaches~19 per cent during the early stage of the 2012-2013 outburst.Avague correlation of P with brightness is observed. There is no preferred electric vector polarization angle and during the outburst the linear polarization vector shows wide rotations in both directions, suggesting a complex behaviour/structure of the jet and possible turbulence. The analysis of 140 optical spectra acquired at the Steward Observatory reveals a strong Mg II broad emission line with an essentially stable flux of 6.2 × 10-15 erg cm-2 s-1 and a full width at half-maximum of 2053 km s-1.

48. Synchrotron emission from the blazar PG 1553+113. An analysis of its flux and polarization variability

Author

Raiteri C., Nicastro F., Stamerra A., Villata M., Larionov V., Blinov D., Acosta-Pulido J., Arévalo M., Arkharov A., Bachev R., Borman G., Carnerero M., Carosati D., Cecconi M., Chen W., Damljanovic G., Di Paola A., Ehgamberdiev S., Frasca A., Giroletti M., González-Morales P., Griñon-Marín A., Grishina T., Huang P., Ibryamov S., Klimanov S., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto G., Liodakis I., Martínez-Lombilla C., Mihov B., Mirzaqulov D., Mokrushina A., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Panopoulou G., Pastor Yabar A., Pinna F., Protasio C., Rizzi N., Sadun A., Savchenko S., Semkov E., Sigua L., Slavcheva-Mihova L., Strigachev A., Tornikoski M., Troitskaya Y., Troitsky I., Vasilyev A., Vera R., Vince O., Zanmar Sanchez R., Raiteri C., Nicastro F., Stamerra A., Villata M., Larionov V., Blinov D., Acosta-Pulido J., Arévalo M., Arkharov A., Bachev R., Borman G., Carnerero M., Carosati D., Cecconi M., Chen W., Damljanovic G., Di Paola A., Ehgamberdiev S., Frasca A., Giroletti M., González-Morales P., Griñon-Marín A., Grishina T., Huang P., Ibryamov S., Klimanov S., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto G., Liodakis I., Martínez-Lombilla C., Mihov B., Mirzaqulov D., Mokrushina A., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Panopoulou G., Pastor Yabar A., Pinna F., Protasio C., Rizzi N., Sadun A., Savchenko S., Semkov E., Sigua L., Slavcheva-Mihova L., Strigachev A., Tornikoski M., Troitskaya Y., Troitsky I., Vasilyev A., Vera R., Vince O., and Zanmar Sanchez R.

Abstract

© 2016 The Authors.In 2015 July 29-September 1, the satellite XMM-Newton pointed at the BL Lac object PG 1553+133 six times, collecting data for 218 h. During one of these epochs, simultaneous observations by the Swift satellite were requested to compare the results of the X-ray and optical-UV instruments. Optical, near-infrared and radio monitoring was carried out by the Whole Earth Blazar Telescope (WEBT) collaboration for the whole observing season. We here present the results of the analysis of all these data, together with an investigation of the source photometric and polarimetric behaviour over the last 3 yr. The 2015 EPIC spectra show slight curvature and the corresponding light curves display fast X-ray variability with a time-scale of the order of 1 h. In contrast to previous results, during the brightest X-ray states detected in 2015 the simple log-parabolic model that best fits the XMM-Newton data also reproduces reasonably well the whole synchrotron bump, suggesting a peak in the near- UV band. We found evidence of a wide rotation of the polarization angle in 2014, when the polarization degree was variable, but the flux remained almost constant. This is difficult to interpret with deterministic jet emission models, while it can be easily reproduced by assuming some turbulence of the magnetic field.

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

Author

Raiteri C., Villata M., Acosta-Pulido J., Agudo I., Arkharov A., Bachev R., Baida G., Benítez E., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carnerero M., Carosati D., Casadio C., Castro-Segura N., Chen W., Damljanovic G., D'Ammando F., Di Paola A., Echevarría J., Efimova N., Ehgamberdiev S., Espinosa C., Fuentes A., Giunta A., Gómez J., Grishina T., Gurwell M., Hiriart D., Jermak H., Jordan B., Jorstad S., Joshi M., Kopatskaya E., Kuratov K., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionov V., Larionova E., Larionova L., Lázaro C., Lin C., Malmrose M., Marscher A., Matsumoto K., McBreen B., Michel R., Mihov B., Minev M., Mirzaqulov D., Mokrushina A., Molina S., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Okhmat D., Ovcharov E., Pinna F., Polakis T., Protasio C., Pursimo T., Redondo-Lorenzo F., Rizzi N., Rodriguez-Coira G., Sadakane K., Sadun A., Samal M., Savchenko S., Semkov E., Skiff B., Slavcheva-Mihova L., Smith P., Steele I., Raiteri C., Villata M., Acosta-Pulido J., Agudo I., Arkharov A., Bachev R., Baida G., Benítez E., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carnerero M., Carosati D., Casadio C., Castro-Segura N., Chen W., Damljanovic G., D'Ammando F., Di Paola A., Echevarría J., Efimova N., Ehgamberdiev S., Espinosa C., Fuentes A., Giunta A., Gómez J., Grishina T., Gurwell M., Hiriart D., Jermak H., Jordan B., Jorstad S., Joshi M., Kopatskaya E., Kuratov K., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionov V., Larionova E., Larionova L., Lázaro C., Lin C., Malmrose M., Marscher A., Matsumoto K., McBreen B., Michel R., Mihov B., Minev M., Mirzaqulov D., Mokrushina A., Molina S., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Okhmat D., Ovcharov E., Pinna F., Polakis T., Protasio C., Pursimo T., Redondo-Lorenzo F., Rizzi N., Rodriguez-Coira G., Sadakane K., Sadun A., Samal M., Savchenko S., Semkov E., Skiff B., Slavcheva-Mihova L., Smith P., and Steele I.

Abstract

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions - such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution - can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016-2017 (brightness increase of six ma

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

Author

Raiteri C., Villata M., Acosta-Pulido J., Agudo I., Arkharov A., Bachev R., Baida G., Benítez E., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carnerero M., Carosati D., Casadio C., Castro-Segura N., Chen W., Damljanovic G., D'Ammando F., Di Paola A., Echevarría J., Efimova N., Ehgamberdiev S., Espinosa C., Fuentes A., Giunta A., Gómez J., Grishina T., Gurwell M., Hiriart D., Jermak H., Jordan B., Jorstad S., Joshi M., Kopatskaya E., Kuratov K., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionov V., Larionova E., Larionova L., Lázaro C., Lin C., Malmrose M., Marscher A., Matsumoto K., McBreen B., Michel R., Mihov B., Minev M., Mirzaqulov D., Mokrushina A., Molina S., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Okhmat D., Ovcharov E., Pinna F., Polakis T., Protasio C., Pursimo T., Redondo-Lorenzo F., Rizzi N., Rodriguez-Coira G., Sadakane K., Sadun A., Samal M., Savchenko S., Semkov E., Skiff B., Slavcheva-Mihova L., Smith P., Steele I., Raiteri C., Villata M., Acosta-Pulido J., Agudo I., Arkharov A., Bachev R., Baida G., Benítez E., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carnerero M., Carosati D., Casadio C., Castro-Segura N., Chen W., Damljanovic G., D'Ammando F., Di Paola A., Echevarría J., Efimova N., Ehgamberdiev S., Espinosa C., Fuentes A., Giunta A., Gómez J., Grishina T., Gurwell M., Hiriart D., Jermak H., Jordan B., Jorstad S., Joshi M., Kopatskaya E., Kuratov K., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionov V., Larionova E., Larionova L., Lázaro C., Lin C., Malmrose M., Marscher A., Matsumoto K., McBreen B., Michel R., Mihov B., Minev M., Mirzaqulov D., Mokrushina A., Molina S., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Okhmat D., Ovcharov E., Pinna F., Polakis T., Protasio C., Pursimo T., Redondo-Lorenzo F., Rizzi N., Rodriguez-Coira G., Sadakane K., Sadun A., Samal M., Savchenko S., Semkov E., Skiff B., Slavcheva-Mihova L., Smith P., and Steele I.

Abstract

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions - such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution - can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016-2017 (brightness increase of six ma

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