We report the detection by the AGILE (Astro-rivelatore Gamma a Immagini LEggero) satellite of an intense gamma-ray flare from the source AGL J1511-0909, associated with the powerful quasar PKS 1510-089, during ten days of observations from 23 August to 1 September 2007. Aims: During the observation period, the source was in optical decrease following a flaring event monitored by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT). The simultaneous gamma-ray, optical, and radio coverage allows us to study the spectral energy distribution and the theoretical models based on the synchrotron and inverse Compton (IC) emission mechanisms. Methods: AGILE observed the source with its two co-aligned imagers, the Gamma-Ray Imaging Detector and the hard X-ray imager Super-AGILE sensitive in the 30 MeV - 50 GeV and 18 - 60 keV bands, respectively. Results: Between 23 and 27 August 2007, AGILE detected gamma-ray emission from PKS 1510-089 when this source was located at about 50° off-axis, with an average flux of (270 ± 65) x 10-8 photons cm-2 s-1 for photon energy above 100 MeV. In the following period, 28 August-1 September, after a satellite re-pointing, AGILE detected the source at about 35° off-axis, with an average flux (E > 100 MeV) of (195 ± 30) x 10-8 photons cm-2 s-1. No emission was detected by Super-AGILE, with a 3-sigma upper limit of 45 mCrab in 200 ks. Conclusions: The spectral energy distribution is modelled with a homogeneous one-zone synchrotron self Compton (SSC) emission plus contributions by external photons: the SSC emission contributes primarily to the X-ray band, whereas the contribution of the IC from the external disc and the broad line region match the hard gamma-ray spectrum observed.
|Titolo:||AGILE Detection of Intense Gamma-Ray Emission from the Blazar PKS 1510-089|
|Data di pubblicazione:||1-nov-2008|
|Appare nelle tipologie:||1.1 Articolo in rivista|