The 2009 December Gamma-ray Flare of 3C 454.3: The Multifrequency Campaign
Sakamoto, T.; Pian, E.; Fugazza, D.; Tiengo, A.; Costa, E.; Mereghetti, S.; Barbiellini, G.; Longo, F.; Morselli, A.; Chen, A. W.; Colafrancesco, S.; Giommi, P.; Itoh, R.; Villata, M.; Di Cocco, G.; Raiteri, C. M.; Pellizzoni, A.; Sadun, A. C.; Pilia, M.; Larionov, V. M.; Tornikoski, M.; Gianotti, F.; Feroci, M.; Falcone, A. D.; Leto, P.; Curran, P. A.; Aller, H. D.; Aller, M. F.; D'Ammando, F.; Del Monte, E.; Donnarumma, I.; Evangelista, Y.; Soffitta, P.; Trois, A.; Moretti, E.; Vercellone, S.; Pacciani, L.; Yamanaka, M.; Uemura, M.; Verrecchia, F.; Striani, E.; Vittorini, V.; Tavani, M.; Bulgarelli, A.; Giuliani, A.; Pucella, G.; Argan, A.; Caraveo, P.; Cattaneo, P. W.; De Paris, G.; Ferrari, A.; Fiorini, M.; Fuschino, F.; Galli, M.; Labanti, C.; Lapshov, I.; Lazzarotto, F.; Lipari, P.; Marisaldi, M.; Morelli, E.; Perotti, F.; Piano, G.; Picozza, P.; Prest, M.; Rapisarda, M.; Rappoldi, A.; Rubini, A.; Sabatini, S.; Trifoglio, M.; Vallazza, E.; Zanello, D.; Pittori, C.; Santolamazza, P.; Lucarelli, F.; Salotti, L.; Berdyugin, A.; Fiocchi, M. T.; Gurwell, M. A.; Krimm, H. A.; Stroh, M. C.; Takalo, L. O.; Sasada, M.; Lin, C. S.; Lahteenmaki, A.
Italy, United States, Japan, United Kingdom, Finland, Taiwan, Russia
Abstract
During the month of 2009 December, the blazar 3C 454.3 became the brightest gamma-ray source in the sky, reaching a peak flux F ~ 2000 × 10-8 photons cm-2 s-1 for E > 100 MeV. Starting in 2009 November intensive multifrequency campaigns monitored the 3C 454 gamma-ray outburst. Here, we report on the results of a two-month campaign involving AGILE, INTEGRAL, Swift/XRT, Swift/BAT, and Rossi XTE for the high-energy observations and Swift/UVOT, KANATA, Goddard Robotic Telescope, and REM for the near-IR/optical/UV data. GASP/WEBT provided radio and additional optical data. We detected a long-term active emission phase lasting ~1 month at all wavelengths: in the gamma-ray band, peak emission was reached on 2009 December 2-3. Remarkably, this gamma-ray super-flare was not accompanied by correspondingly intense emission in the optical/UV band that reached a level substantially lower than the previous observations in 2007-2008. The lack of strong simultaneous optical brightening during the super-flare and the determination of the broadband spectral evolution severely constrain the theoretical modeling. We find that the pre- and post-flare broadband behavior can be explained by a one-zone model involving synchrotron self-Compton plus external Compton emission from an accretion disk and a broad-line region. However, the spectra of the 2009 December 2-3 super-flare and of the secondary peak emission on 2009 December 9 cannot be satisfactorily modeled by a simple one-zone model. An additional particle component is most likely active during these states.