The 2009 December gamma-ray flare of 3C 454.3: the multifrequency campaign
Pacciani, L. ; Vittorini, V. ; Tavani, M. ; Colafrancesco, S. ; Giommi, P. ; Salotti, L.
Jun - 2010
DOI: 10.1088/2041-8205/716/2/L170
ISSN : 2041-8205 ;
journal : The Astrophysical Journal

Volume : 716 ; Issue : 2
type: Article Journal

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 × 108 photons cm2 s1 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.

keywords : galaxies: active; galaxies: individual (3C 454.3); quasars: general; radiation mechanisms: non-thermal