M. Hayashida, G. M. Madejski, K. Nalewajko, M. Sikora, A. E. Wehrle, P. Ogle, W. Collmar, S. Larsson, Y. Fukazawa, R. Itoh, J. Chiang, L. Stawarz, R. D. Blandford, J. L. Richards, W. Max-Moerbeck, A. Readhead, R. Buehler, E. Cavazzuti, S. Ciprini, N. Gehrels, A. Reimer, A. Szostek, T. Tanaka, G. Tosti, Y. Uchiyama, K. S. Kawabata, M. Kino, K. Sakimoto, M. Sasada, S. Sato, M. Uemura, M. Yamanaka, J. Greiner, T. Kruehler, A. Rossi, J. P. Macquart, D. C. -J. Bock, M. Villata, C. M. Raiteri, I. Agudo, H. D. Aller, M. F. Aller, A. A. Arkharov, U. Bach, E. Benitez, A. Berdyugin, D. A. Blinov, K. Blumenthal, M. Boettcher, C. S. Buemi, D. Carosati, W. P. Chen, A. Di Paola, M. Dolci, N. V. Efimova, E. Forne, J. L. Gomez, M. A. Gurwell, J. Heidt, D. Hiriart, B. Jordan, S. G. Jorstad, M. Joshi, G. Kimeridze, T. S. Konstantinova, E. N. Kopatskaya, E. Koptelova, O. M. Kurtanidze, A. Lahteenmaki, A. Lamerato, V. M. Larionov, E. G. Larionova, L. V. Larionova, P. Leto, E. Lindfors, A. P. Marscher, I. M. McHardy, S. N. Molina, D. A. Morozova, M. G. Nikolashvili, K. Nilsson, R. Reinthal, P. Roustazadeh, T. Sakamoto, L. A. Sigua, A. Sillanpaa, L. Takalo, J. Tammi, B. Taylor, M. Tornikoski, C. Trigilio, I. S. Troitsky, G. Umana
We present time-resolved broad-band observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears delayed with respect to the gamma-ray emission by about 10 days. X-ray observations reveal a pair of `isolated' flares separated by ~90 days, with only weak gamma-ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the gamma-ray flare, while the peak appears in the mm/sub-mm band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broad-band spectra during the gamma-ray flaring event by a shift of its location from ~ 1 pc to ~ 4 pc from the central black hole. On the other hand, if the gamma-ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission.
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http://arxiv.org/abs/1206.0745
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