AGILE observation of a gamma-ray flare from the blazar 3C 279
Abstract
Context: We report the detection by the AGILE satellite of an intense gamma-ray flare from the gamma-ray source 3EG J1255-0549, associated with the Flat Spectrum Radio Quasar 3C 279, during the AGILE pointings towards the Virgo Region on 2007 July 9-13.
Aims: The simultaneous optical, X-ray and gamma-ray covering allows us to study the spectral energy distribution (SED) and the theoretical models relative to the mid-July flaring episode.
Methods: AGILE observed the source during its Science Performance Verification Phase with its two co-aligned imagers: the Gamma-Ray Imaging Detector (GRID) and the hard X-ray imager (Super-AGILE) sensitive in the 30 MeV-50 GeV and 18-60 keV respectively. During the AGILE observation the source was monitored simultaneously in the optical band by the REM telescope and in the X-ray band by the Swift satellite through 4 target of opportunity observations.
Results: During 2007 July 9-13, AGILE-GRID detected gamma-ray emission from 3C 279, with the source at ~2° from the center of the field of view, with an average flux of (210 ± 38) × 10-8 ph cm-2 s-1 for energy above 100 MeV. No emission was detected by Super-AGILE, with a 3-σ upper limit of 10 mCrab. During the observation, which lasted about 4 days, no significative gamma-ray flux variation was observed.
Conclusions: The Spectral Energy Distribution is modelled with a homogeneous one-zone Synchrotron Self Compton emission plus the contributions by external Compton scattering of the direct disk radiation and, to a lesser extent, by external Compton scattering of photons from the Broad Line Region.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2009
- DOI:
- 10.1051/0004-6361:200810785
- arXiv:
- arXiv:0810.2189
- Bibcode:
- 2009A&A...494..509G
- Keywords:
-
- gamma rays: observations;
- galaxies: quasars: individual: 3C 279;
- Astrophysics
- E-Print:
- Accepted for publication in Astronomy and Astrophysics