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1. Polarization angle swings in blazars: The case of 3C 279

Author

A. Berdyugin, G. A. Borman, Dmitry A. Blinov, Tuomas Savolainen, J. M. Lopez, Vladimir A. Hagen-Thorn, Frank K. Schinzel, Tom Krajci, Yuki Moritani, Michitoshi Yoshida, A. C. Sadun, S. N. Molina, T. S. Grishina, Hiroshi Akitaya, V. E. Zhdanova, Sergey S. Savchenko, Kirill Sokolovsky, Leo O. Takalo, Elina Lindfors, N. V. Efimova, S. V. Nazarov, L. V. Larionova, José L. Gómez, O. I. Spiridonova, J. A. Zensus, T. Ui, Jochen Heidt, Alan P. Marscher, Yasushi Fukazawa, Manasvita Joshi, S. G. Sergeev, Elena G. Larionova, Brian Taylor, Kari Nilsson, L. S. Ugolkova, Daria A. Morozova, Ryosuke Itoh, R. Reinthal, Carolina Casadio, Ian M. McHardy, Erika Benítez, I. Korobtsev, A. N. Burenkov, N. G. Bochkarev, Ivan S. Troitsky, Paul S. Smith, Makoto Uemura, Koji S. Kawabata, Mahito Sasada, Valeri M. Larionov, E. N. Kopatskaya, V. T. Doroshenko, S. O. Kurtanidze, Svetlana G. Jorstad, M. Sorcia, N. G. Pulatova, Ivan Agudo, G. N. Kimeridze, David Hiriart, O. M. Kurtanidze, Sebastian Kiehlmann, Maria G. Nikolashvili, Katsutoshi Takaki, L. A. Sigua, International Max Planck Research Schools, Academy of Finland, National Aeronautics and Space Administration (US), Russian Foundation for Basic Research, Universidad Nacional Autónoma de México, Ministerio de Economía y Competitividad (España), and Junta de Andalucía

Subjects
Physics, active [Galaxies], 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics, Galaxies: active, 01 natural sciences, Max planck institute, individual: 3C 279 [Quasars], Space and Planetary Science, Basic research, Galaxies: jets, Polarization, 0103 physical sciences, Christian ministry, jets [Galaxies], 010303 astronomy & astrophysics, Quasars: individual: 3C 279
Abstract

Kiehlmann, S. et. al., Context. Over the past few years, on several occasions, large, continuous rotations of the electric vector position angle (EVPA) of linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy gamma-ray flares and they have attracted considerable attention, since they could allow us to probe the magnetic field structure in the gamma-ray emitting region of the jet. The flat-spectrum radio quasar 3C 279 is one of the most prominent examples showing this behaviour. Aims. Our goal is to study the observed EVPA rotations and to distinguish between a stochastic and a deterministic origin of the polarization variability. Methods. We have combined multiple data sets of R-band photometry and optical polarimetry measurements of 3C 279, yielding exceptionally well-sampled flux density and polarization curves that cover a period of 2008-2012. Several large EVPA rotations are identified in the data. We introduce a quantitative measure for the EVPA curve smoothness, which is then used to test a set of simple random walk polarization variability models against the data. Results. 3C 279 shows different polarization variation characteristics during an optical low-flux state and a flaring state. The polarization variation during the flaring state, especially the smooth similar to 360 degrees rotation of the EVPA in mid-2011, is not consistent with the tested stochastic processes. Conclusions. We conclude that, during the two different optical flux states, two different processes govern polarization variation, which is possibly a stochastic process during the low-brightness state and a deterministic process during the flaring activity., S.K. was supported for this research through a stipend from the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Max Planck Institute for Radio Astronomy in cooperation with the Universities of Bonn and Cologne. T.S. was partly supported by the Academy of Finland project 274477. The research at Boston University was partly funded by NASA Fermi GI grant NNX11AQ03G. K.V.S. is partly supported by the Russian Foundation for Basic Research grants 13-02-12103 and 14-02-31789. N.G.B. was supported by the RFBR grant 12-02-01237a. E.B., M.S. and D.H. thank financial support from UNAM DGAPA-PAPIIT through grant IN116211-3. I. A. acknowledges support by a Ramon y Cajal grant of the Spanish Ministry of Economy and Competitiveness (MINECO). The research at the IAA-CSIC and the MAPCAT program are supported by the Spanish Ministry of Economy and Competitiveness and the Regional Government of Andalucia (Spain) through grants AYA2010-14844, AYA2013-40825-P, and P09-FQM-4784. The Calar Alto Observatory is jointly operated by the Max-Planck-Institut fur Astronomie and the Instituto de Astrofisica de Andalucia-CSIC. Data from the Steward Observatory spectropolarimetric monitoring project were used. This program is supported by Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX14AQ58G. St. Petersburg University team acknowledges support from Russian RFBR grant 15-02-00949 and St. Petersburg University research grant 6.38.335.2015. The Abastumani team acknowledges financial support of the project FR/638/6-320/12 by the Shota Rustaveli National Science Foundation under contract 31/77.

Published
2016

2. The Brightest Gamma-Ray Flaring Blazar in the Sky: AGILE and Multi-wavelength Observations of 3C 454.3 During 2010 November

Author

Sofia O. Kurtanidze, Valeri M. Larionov, M. F. Aller, Lorand A. Sigua, M. Trifoglio, V. Strelnitski, S. G. Sergeev, Fulvio Gianotti, J. L. Gomez, M. Cardillo, Pietro Ubertini, I. M. McHardy, Angela Bazzano, Fabrizio Lucarelli, Kirill Sokolovsky, C. M. Raiteri, A. Trois, T. Krajci, F. Lazzarotto, Mark Gurwell, I. Donnarumma, A. C. Sadun, Y. Evangelista, G. Walker, Manasvita Joshi, P. Santolamazza, M. Pasanen, D. A. Morozova, R. Reinthal, Elena Pian, M. G. Nikolashvili, M. Tavani, G. A. Borman, P. W. Cattaneo, A. Sillanpää, A. A. Arkharov, L. Maraschi, N. V. Efimova, Givi N. Kimeridze, E. Del Monte, F. Longo, G. Pucella, C. Pittori, K. Nilsson, A. Pellizzoni, E. Striani, V. Vittorini, Marc Türler, V. Bianchin, M. Rapisarda, A. Giuliani, Carlo Ferrigno, P. Soffitta, S. V. Nazarov, Hugh D. Aller, G. Barbiellini, R. A. Chigladze, E. Lindfors, Arnaud Ferrari, F. Verrecchia, S. Sabatini, M. Pilia, M. Villata, M. Giusti, F. Fuschino, Andrei Berdyugin, Uwe Bach, I. Agudo, L. O. Takalo, A. W. Chen, Brian W. Taylor, P. Giommi, Omar M. Kurtanidze, S. N. Molina, J. A. Ros, G. Piano, Stephanie Sallum, M. Feroci, Andrea Bulgarelli, T. Sakamoto, Yu. S. Efimov, P. Romano, S. Vercellone, L. Pacciani, Mariateresa Fiocchi, A. Rappoldi, R. D. Schwartz, S., Vercellone, E., Striani, V., Vittorini, I., Donnarumma, L., Pacciani, G., Pucella, M., Tavani, C. M., Raiteri, M., Villata, P., Romano, M., Fiocchi, A., Bazzano, V., Bianchin, C., Ferrigno, L., Maraschi, E., Pian, M., T\urler, P., Ubertini, A., Bulgarelli, A. W., Chen, A., Giuliani, Longo, Francesco, G., Barbiellini, M., Cardillo, P. W., Cattaneo, Monte, E., Y., Evangelista, M., Feroci, A., Ferrari, F., Fuschino, F., Gianotti, M., Giusti, F., Lazzarotto, A., Pellizzoni, G., Piano, M., Pilia, M., Rapisarda, A., Rappoldi, S., Sabatini, P., Soffitta, M., Trifoglio, A., Troi, P., Giommi, F., Lucarelli, C., Pittori, P., Santolamazza, F., Verrecchia, I., Agudo, H. D., Aller, M. F., Aller, A. A., Arkharov, U., Bach, A., Berdyugin, G. A., Borman, R., Chigladze, Y. S., Efimov, N. V., Efimova, J. L., Gomez, M. A., Gurwell, I. M., Mchardy, M., Joshi, G. N., Kimeridze, T., Krajci, O. M., Kurtanidze, S. O., Kurtanidze, V. M., Larionov, E., Lindfor, S. N., Molina, D. A., Morozova, S. V., Nazarov, M. G., Nikolashvili, K., Nilsson, M., Pasanen, R., Reinthal, J. A., Ro, A. C., Sadun, T., Sakamoto, S., Sallum, S. G., Sergeev, R. D., Schwartz, L. A., Sigua, A., Sillanp\a\a, K. V., Sokolovsky, V., Strelnitski, L., Takalo, B., Taylor, and G., Walker

Subjects
galaxies: active, galaxies: jets, radiation mechanisms: non-thermal, quasars: general, quasars: individual: 3C 454.3, Photon, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Vela, 01 natural sciences, law.invention, Pulsar, law, 0103 physical sciences, Blazar, 010303 astronomy & astrophysics, media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), general [quasars], 010308 nuclear & particles physics, individual: 3C 454.3 [quasars], Gamma ray, Astronomy and Astrophysics, non-thermal [radiation mechanisms], jet [galaxies], Space and Planetary Science, Sky, active [galaxies], Astrophysics - High Energy Astrophysical Phenomena, Flare
Abstract

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

Published
2011

3. Direct Imaging of a Toroidal Magnetic Field in the Inner Jet of NRAO 150

Author

Thomas P. Krichbaum, Iván Agudo, Alan L. Roy, José L. Gómez, Ivan Marti-Vidal, and S. N. Molina

Subjects
jets, Active galactic nucleus, lcsh:Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics, 01 natural sciences, lcsh:QB1-991, symbols.namesake, galaxies, active galactic nuclei, Very Long Baseline Interferometry, 0103 physical sciences, Very-long-baseline interferometry, Faraday effect, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Toroid, 010308 nuclear & particles physics, Astronomy and Astrophysics, Quasar, Polarization (waves), Galaxy, Magnetic field, symbols
Abstract

Most formation models and numerical simulations cause a helical magnetic field to form, accelerate and collimate jets in active galactic nuclei (AGN). For this reason, observational direct evidence for the existence of these helical magnetic fields is of special relevance. In this work, we present ultra- high-resolution observations of the innermost regions of the jet in the quasar NRAO150. We study the polarization structure and report evidence of a helical magnetic field.

Published
2016
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4. Polarization angle swings in blazars: The case of 3C 279(Corrigendum)

Author

Frank K. Schinzel, Vladimir A. Hagen-Thorn, L. V. Larionova, Valeri M. Larionov, S. V. Nazarov, Sebastian Kiehlmann, Dmitry A. Blinov, J. A. Zensus, Makoto Uemura, Givi N. Kimeridze, Sergey S. Savchenko, I. Korobtsev, Yuki Moritani, A. N. Burenkov, L. O. Takalo, Elena G. Larionova, Brian W. Taylor, Alan P. Marscher, V. E. Zhdanova, E. N. Kopatskaya, Michitoshi Yoshida, A. C. Sadun, S. G. Jorstad, S. N. Molina, I. M. McHardy, Lorand A. Sigua, Jochen Heidt, G. A. Borman, J. L. Gomez, Elina Lindfors, T. Krajci, Kirill Sokolovsky, Carolina Casadio, D. A. Morozova, M. G. Nikolashvili, N. G. Bochkarev, Kari Nilsson, R. Reinthal, O. M. Kurtanidze, Hiroshi Akitaya, O. I. Spiridonova, S. G. Sergeev, J. M. Lopez, N. V. Efimova, Manasvita Joshi, Mahito Sasada, N. G. Pulatova, Ivan Agudo, Erika Benítez, David Hiriart, Katsutoshi Takaki, Tuomas Savolainen, Yasushi Fukazawa, Andrei Berdyugin, Paul S. Smith, Ivan S. Troitsky, T. S. Grishina, V. T. Doroshenko, Sofia O. Kurtanidze, M. Sorcia, Koji S. Kawabata, T. Ui, L. S. Ugolkova, and Ryosuke Itoh

Subjects
Physics, Brewster's angle, 010504 meteorology & atmospheric sciences, Astronomy and Astrophysics, Astrophysics, Polarization (waves), 01 natural sciences, symbols.namesake, Space and Planetary Science, 0103 physical sciences, symbols, Blazar, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Published
2016
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5. The Structure and Emission Model of the Relativistic Jet in the Quasar 3C 279 Inferred from Radio to High-energy gamma-Ray Observations in 2008-2010

Author

Mauro Dolci, Koji S. Kawabata, Werner Collmar, M. Hayashida, R. Buehler, S. Ciprini, Krzysztof Nalewajko, Svetlana G. Jorstad, Paolo Leto, E. Lindfors, E. Forné, Yasushi Fukazawa, Walter Max-Moerbeck, Patrick Ogle, Jean-Pierre Macquart, B. Jordan, Alan P. Marscher, N. Gehrels, Merja Tornikoski, Mahito Sasada, R. Itoh, Elena G. Larionova, M. F. Aller, A. A. Arkharov, David Hiriart, Carla Buemi, N. V. Efimova, Yasunobu Uchiyama, G. M. Madejski, Tatiana S. Konstantinova, Mark Gurwell, J. L. Richards, S. N. Molina, Makoto Uemura, Joni Tammi, G. Tosti, Ann E. Wehrle, Susumu Sato, A. Lamerato, E. Cavazzuti, Manasvita Joshi, James Chiang, K. Blumenthal, D. Carosati, Roger Blandford, Hugh D. Aller, T. Sakamoto, Erika Benítez, Dmitry A. Blinov, Douglas C.-J. Bock, A. C. S. Readhead, E. N. Kopatskaya, Givi N. Kimeridze, A. Sillanpää, S. Larsson, Omar M. Kurtanidze, Anne Lähteenmäki, Andrea Rossi, Wen Ping Chen, Ekaterina Koptelova, Valeri M. Larionov, José L. Gómez, I. S. Troitsky, R. Reinthal, Masayuki Yamanaka, D. A. Morozova, C. M. Raiteri, M. Boettcher, K. Nilsson, Jochen Greiner, A. Di Paola, M. Kino, L. V. Larionova, Lukasz Stawarz, M. Sikora, Takaaki Tanaka, Anna Szostek, I. M. McHardy, M. Villata, M. G. Nikolashvili, T. Kruehler, Andrei Berdyugin, Uwe Bach, Corrado Trigilio, I. Agudo, A. Reimer, G. Umana, L. O. Takalo, Brian W. Taylor, Jochen Heidt, K. Sakimoto, P. Roustazadeh, and Lorand A. Sigua

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), galaxies: active, galaxies: jets, gamma rays: galaxies, quasars: individual: 3C 279, radiation mechanisms: non-thermal, X-rays: galaxies, Astrophysics::High Energy Astrophysical Phenomena, jets [galaxies], FOS: Physical sciences, Astrophysics, 01 natural sciences, Spectral line, law.invention, Spitzer Space Telescope, law, 0103 physical sciences, individual (3C 279) [quasars], 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Gamma ray, Astronomy and Astrophysics, Optical polarization, Quasar, non-thermal [radiation mechanisms], Synchrotron, galaxies [X-rays], Space and Planetary Science, active [galaxies], galaxies [gamma rays], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Fermi Gamma-ray Space Telescope, Flare
Abstract

著者人数: 93名, Accepted: 2012-05-30, 資料番号: SA1004165000

Published
2012

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

Author

Neelam Panwar, M. J. Arévalo, Clemens Thum, Antoniya Valcheva, Mark Gurwell, Elena G. Larionova, R. D. Schwartz, S. N. Molina, Evgeni Ovcharov, M. Pasanen, J. Leon-Tavares, J. A. Ros, A. Di Paola, L. V. Larionova, Svetlana G. Jorstad, H. C. Lin, K. Blumenthal, A. Sillanpää, Tatiana S. Konstantinova, D. O. Mirzaqulov, D. A. Morozova, R. Reinthal, Jochen Heidt, Carolina Casadio, Anne Lähteenmäki, Ekaterina Koptelova, Sh. A. Ehgamberdiev, David Hiriart, Merja Tornikoski, J. A. Acosta-Pulido, D. Carosati, Mauro Dolci, G. M. Richter, Ann E. Wehrle, A. I. Gonzále, I. Agudo, T. M. Carleton, José L. Gómez, I. M. McHardy, Alan P. Marscher, I. S. Troitsky, I. Puerto-Gimenez, M. G. Nikolashvili, E. N. Kopatskaya, Paolo Leto, Corrado Trigilio, G. Umana, N. Smith, T. Sakamoto, Kari Nilsson, Omar M. Kurtanidze, Wen Ping Chen, Sofia O. Kurtanidze, Raúl Mújica, A. Bueno, Filippo D'Ammando, C. M. Raiteri, L. O. Takalo, Valeri M. Larionov, Brian W. Taylor, M. I. Carnerero, Sh. Holikov, A. A. Arkharov, N. V. Efimova, Joni Tammi, Manasvita Joshi, Paul S. Smith, M. Villata, Andrei Berdyugin, Erika Benítez, U. Bach, Dmitry A. Blinov, Hugh D. Aller, V. A. Hagen-Thorn, M. F. Aller, Elina Lindfors, Carla Buemi, Anne Lähteenmäki Group, Aalto-yliopisto, Aalto University, Raiteri CM, Villata M, Smith PS, Larionov VM, Acosta-Pulido JA, Aller MF, DAmmando F, Gurwell MA, Jorstad SG, Joshi M, Kurtanidze OM, Lahteenmaki A, Mirzaqulov DO, Agudo I, Aller HD, Arevalo MJ, Arkharov AA, Bach U, Benitez E, Berdyugin A, Blinov DA, Blumenthal K, Buemi CS, Bueno A, Carleton TM, Carnerero MI, Carosati D, Casadio C, Chen WP, Di Paola A, Dolci M, Efimova NV, Ehgamberdiev SA, Gomez JL, Gonzalez AI, Hagen-Thorn VA, Heidt J, Hiriart D, Holikov S, Konstantinova TS, Kopatskaya EN, Koptelova E, Kurtanidze SO, Larionova EG, Larionova LV, Leon-Tavares J, Leto P, Lin HC, Lindfors E, Marscher AP, McHardy IM, Molina SN, Morozova DA, Mujica R, Nikolashvili MG, Nilsson K, Ovcharov EP, Panwar N, Pasanen M, Puerto-Gimenez I, Reinthal R, Richter GM, Ros JA, Sakamoto T, Schwartz RD, Sillanpaa A, Smith N, Takalo LO, Tammi J, Taylor B, Thum C, Tornikoski M, Trigilio C, Troitsky IS, Umana G, Valcheva AT, and Wehrle AE

Subjects
Brightness, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, education, jets [galaxies], Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, individual: 4C 38.41 [quasars], 0103 physical sciences, Blazar, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Jet (fluid), Line-of-sight, general [quasars], 010308 nuclear & particles physics, Astronomy and Astrophysics, Viewing angle, Light curve, galaxies: active – quasars: general – quasars: individual: 4C 38.41 – galaxies: jets, 13. Climate action, Space and Planetary Science, active [galaxies], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Fermi Gamma-ray Space Telescope
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

7. The long-lasting activity of 3C 454.3: GASP-WEBT and satellite observations in 2008-2010

Author

C. M. Raiteri, M. Villata, M. F. Aller, M. A. Gurwell, O. M. Kurtanidze, A. Lähteenmäki, V. M. Larionov, P. Romano, S. Vercellone, I. Agudo, H. D. Aller, A. A. Arkharov, U. Bach, E. Benítez, A. Berdyugin, D. A. Blinov, E. V. Borisova, M. Böttcher, O. J. A. Bravo Calle, C. S. Buemi, P. Calcidese, D. Carosati, R. Casas, W.-P. Chen, N. V. Efimova, J. L. Gómez, C. Gusbar, K. Hawkins, J. Heidt, D. Hiriart, H. Y. Hsiao, B. Jordan, S. G. Jorstad, M. Joshi, G. N. Kimeridze, E. Koptelova, T. S. Konstantinova, E. N. Kopatskaya, S. O. Kurtanidze, E. G. Larionova, L. V. Larionova, P. Leto, Y. Li, R. Ligustri, E. Lindfors, M. Lister, A. P. Marscher, S. N. Molina, D. A. Morozova, E. Nieppola, M. G. Nikolashvili, K. Nilsson, N. Palma, M. Pasanen, R. Reinthal, V. Roberts, J. A. Ros, P. Roustazadeh, A. C. Sadun, T. Sakamoto, R. D. Schwartz, L. A. Sigua, A. Sillanpää, L. O. Takalo, J. Tammi, B. Taylor, M. Tornikoski, C. Trigilio, I. S. Troitsky, G. Umana, A. Volvach, T. A. Yuldasheva, Anne Lähteenmäki Group, Aalto-yliopisto, and Aalto University

Subjects
Photon, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, education, jets [galaxies], quasars: individual: 3C 454.3 [galaxies], Synchrotron radiation, Flux, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, law, 0103 physical sciences, 010303 astronomy & astrophysics, Physics, 010308 nuclear & particles physics, quasars: general [galaxies], Astronomy and Astrophysics, Light curve, Synchrotron, Wavelength, Amplitude, 13. Climate action, Space and Planetary Science, active [galaxies], Fermi Gamma-ray Space Telescope, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present multiwavelength observations of 3C 454.3 from April 2008 to March 2010. The radio to optical data are mostly from the GASP-WEBT, UV and X-ray data from Swift, and gamma-ray data from the AGILE and Fermi satellites. We improved the calibration of optical-UV data from the UVOT and OM instruments and estimated the Lyalpha flux to disentangle the contributions from different components in this spectral region. The observations reveal prominent variability above 8 GHz. In the optical-UV band, the variability amplitude decreases with increasing frequency due to a steadier radiation from both a broad line region and an accretion disc. The optical flux reaches nearly the same levels in the 2008-2009 and 2009-2010 observing seasons; the mm one shows similar behaviour, whereas the gamma and X-ray flux levels rise in the second period. Two prominent gamma-ray flares in mid 2008 and late 2009 show a double-peaked structure, with a variable gamma/optical flux ratio. The X-ray flux variations seem to follow the gamma-ray and optical ones by about 0.5 and 1 d, respectively. We interpret the multifrequency behaviour in terms of an inhomogeneous curved jet, where synchrotron radiation of increasing wavelength is produced in progressively outer and wider jet regions, which can change their orientation in time. In particular, we assume that the long-term variability is due to this geometrical effect. By combining the optical and mm light curves to fit the gamma and X-ray ones, we find that the gamma (X-ray) emission may be explained by inverse-Comptonisation of synchrotron optical (IR) photons by their parent relativistic electrons (SSC process). A slight, variable misalignment between the synchrotron and Comptonisation zones would explain the increased gamma and X-ray flux levels in 2009-2010, as well as the change in the gamma/optical flux ratio during the outbursts peaks., 17 pages, 9 figures, accepted for publication in A&A

Published
2011

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