AGILE detection of variable gamma-ray activity from the blazar S5 0716+714 during September-October 2007
Abstract
We report the gamma-ray activity from the Intermediate BL Lac S5 0716+714 during 2007 September-October observations by the AGILE satellite, coincident with a period of intense optical activity of the source monitored by GASP-WEBT. AGILE observed the source with its two co-aligned imagers, the Gamma-Ray Imaging Detector (GRID) and the hard X-ray imager (Super-AGILE) sensitive in the energy range 30 MeV-50 GeV and 18-60 keV respectively, in two different periods: the first between 4 and 23 September 2007, the second between 24 October and 1 November 2007. Over the period 7-12 September, AGILE detected gamma-ray emission from the source at a significance level of 9.6-sigma with an average flux (E>100 MeV) of (97+/-15) x 10^{-8} photons cm^{-2} s^{-1}, increasing by a factor of at least four within three days. No emission was detected by Super-AGILE in the energy range 18-60 keV, with a 3-sigma upper limit of 10 mCrab in 335 ksec. The gamma-ray flux of S5 0716+714 detected by AGILE is the highest ever detected for this blazar and one of the most intense gamma-ray fluxes detected from a BL Lac object. The Spectral Energy Distribution (SED) of mid-September seems to be consistent with the synchrotron self-Compton (SSC) emission model, but only by including two SSC components with different variability. In October 2007 AGILE repointed toward S5 0716+714 following an intense optical flare, measuring an average flux of (47+/-11) x 10^{-8} photons cm^{-2} s^{-1} at a significance level of 6.0-sigma. The gamma-ray flux during both AGILE pointings appears to be highly variable on timescales of 1 day.
Keywords
Cite
@article{arxiv.0808.3673,
title = {AGILE detection of variable gamma-ray activity from the blazar S5 0716+714 during September-October 2007},
author = {F. D'Ammando and A. W. Chen and M. Villata and C. M. Raiteri and V. Vittorini and A. Bulgarelli and I. Donnarumma and A. Giuliani and F. Longo and L. Pacciani and G. Pucella and M. Tavani and S. Vercellone},
journal= {arXiv preprint arXiv:0808.3673},
year = {2009}
}
Comments
8 pages, 4 figures, "Workshop on Blazar Variability across the Electromagnetic Spectrum", 2008 April 22-25, Palaiseau, France