Issue |
A&A
Volume 552, April 2013
|
|
---|---|---|
Article Number | A11 | |
Number of page(s) | 24 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201321058 | |
Published online | 13 March 2013 |
Radio to gamma-ray variability study of blazar S5 0716+714
1 Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: brani@mpifr-bonn.mpg.de
2 Astrophysical Institute, Department of Physics and Astronomy, Ohio University Athens, OH 45701, USA
3 Centre for Space Research, North-West University, Potchefstroom Campus, 2531 Potchefstroom, South Africa
4 Université Bordeaux 1, CNRS/IN2p3, Centre d’Études Nucléaires de Bordeaux-Gradignan, 33175 Gradignan, France
5 Astronomy Department, University of Michigan, Ann Arbor, MI 48109-1042, USA
6 Istituto Nazionale di Fisica Nucleare, Sezione di Padova, 35131 Padova, Italy
7 Dipartimento di Fisica e Astronomia, Università di Padova, 35131 Padova, Italy
8 Dept. of Astronomy and Astrophysics, Penn State University, University Park, PA 16802, USA
9 Department of Physical Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526 Hiroshima, Japan
10 FÖMI Satellite Geodetic Observatory, PO Box 585, 1592 Budapest, Hungary
11 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, 1121 Budapest, Hungary
12 Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, 263 129 Nainital, India
13 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
14 Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526 Hiroshima, Japan
15 IRAM, 300 rue de la piscine, 38406 Saint-Martin d’Hères, France
16 Aalto University Metsähovi Radio Observatory, Kylmälä, Finland
17 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, 830011 Urumqi, PR China
18 Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
19 Instituto de Radioastronomía Milimétrica (IRAM), Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain
20 CAB, INTA-CSIC, Ctra. de Torrejón a Ajalvir, km 4, 28850, Torrejón de Ardoz, Madrid, Spain
21 Purdue University, Department of Physics, 525 Northwestern Ave, West Lafayette, IN 47907, USA
22 Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, 606-8502 Kyoto, Japan
23 Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow, Russia
Received: 8 January 2013
Accepted: 29 January 2013
We present the results of a series of radio, optical, X-ray, and γ-ray observations of the BL Lac object S50716+714 carried out between April 2007 and January 2011. The multifrequency observations were obtained using several ground- and space-based facilities. The intense optical monitoring of the source reveals faster repetitive variations superimposed on a long-term variability trend on a time scale of ~350 days. Episodes of fast variability recur on time scales of ~60−70 days. The intense and simultaneous activity at optical and γ-ray frequencies favors the synchrotron self-Compton mechanism for the production of the high-energy emission. Two major low-peaking radio flares were observed during this high optical/γ-ray activity period. The radio flares are characterized by a rising and a decaying stage and agrees with the formation of a shock and its evolution. We found that the evolution of the radio flares requires a geometrical variation in addition to intrinsic variations of the source. Different estimates yield robust and self-consistent lower limits of δ ≥ 20 and equipartition magnetic field Beq ≥ 0.36 G. Causality arguments constrain the size of emission region θ ≤ 0.004 mas. We found a significant correlation between flux variations at radio frequencies with those at optical and γ-rays. Theoptical/GeV flux variations lead the radio variability by ~65 days. The longer time delays between low-peaking radio outbursts and optical flares imply that optical flares are the precursors of radio ones. An orphan X-ray flare challenges the simple, one-zone emission models, rendering them too simple. Here we also describe the spectral energy distribution modeling of the source from simultaneous data taken through different activity periods.
Key words: galaxies: active / BL Lacertae objects: individual: S5 0716+714 / gamma rays: galaxies / X-rays: galaxies / radio continuum: galaxies
© ESO, 2013
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