A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Radio to gamma-ray variability study of blazar S5 0716+714
Tekijät: Rani B, Krichbaum TP, Fuhrmann L, Bottcher M, Lott B, Aller HD, Aller MF, Angelakis E, Bach U, Bastieri D, Falcone AD, Fukazawa Y, Gabanyi KE, Gupta AC, Gurwell M, Itoh R, Kawabata KS, Krips M, Lahteenmaki AA, Liu X, Marchili N, Max-Moerbeck W, Nestoras I, Nieppola E, Quintana-Lacaci G, Readhead ACS, Richards JL, Sasada M, Sievers A, Sokolovsky K, Stroh M, Tammi J, Tornikoski M, Uemura M, Ungerechts H, Urano T, Zensus JA
Kustantaja: EDP SCIENCES S A
Julkaisuvuosi: 2013
Lehti: Astronomy and Astrophysics
Tietokannassa oleva lehden nimi: ASTRONOMY & ASTROPHYSICS
Lehden akronyymi: ASTRON ASTROPHYS
Artikkelin numero: ARTN A11
Vuosikerta: 552
Sivujen määrä: 24
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201321058
We present the results of a series of radio, optical, X-ray, and gamma-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 similar to 350 days. Episodes of fast variability recur on time scales of similar to 60-70 days. The intense and simultaneous activity at optical and gamma-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/gamma-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 delta >= 20 and equipartition magnetic field B-eq >= 0.36 G. Causality arguments constrain the size of emission region theta <= 0.004 mas. We found a significant correlation between flux variations at radio frequencies with those at optical and gamma-rays. The optical/GeV flux variations lead the radio variability by similar to 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.
