AGILE detection of a rapid gamma-ray flare from the blazar PKS 1510-089 during the GASP-WEBT monitoring
Creators: name: D'Ammando, F.
name: Pucella, G.
name: Raiteri, C. M.
name: Villata, M.
name: Vittorini, V.
name: Vercellone, S.
name: Donnarumma, I.
name: Longo, F.
name: Tavani, M.
name: Argan, A.
name: Barbiellini, G.
name: Boffelli, F.
name: Bulgarelli, A.
name: Caraveo, P.
name: Cattaneo, P. W.
name: Chen, A. W.
name: Cocco, V.
name: Costa, E.
name: Del Monte, E.
name: De Paris, G.
name: Di Cocco, G.
name: Evangelista, Y.
name: Feroci, M.
name: Ferrari, A.
name: Fiorini, M.
name: Froysland, T.
name: Fuschino, F.
name: Galli, M.
name: Gianotti, F.
name: Giuliani, A.
name: Labanti, C.
name: Lapshov, I.
name: Lazzarotto, F.
name: Lipari, P.
name: Marisaldi, M.
name: Mereghetti, S.
name: Morselli, A.
name: Pacciani, L.
name: Pellizzoni, A.
name: Perotti, F.
name: Piano, G.
name: Picozza, P.
name: Pilia, M.
name: Prest, M.
name: Rapisarda, M.
name: Rappoldi, A.
name: Sabatini, S.
name: Soffitta, P.
name: Trifoglio, M.
name: Trois, A.
name: Vallazza, E.
name: Zambra, A.
name: Zanello, D.
name: Agudo, I.
name: Aller, M. F.
name: Aller, H. D.
name: Arkharov, A. A.
name: Bach, U.
name: Benitez, E.
name: Berdyugin, A.
name: Blinov, D. A.
name: Buemi, C. S.
name: Chen, W. P.
name: Di Paola, A.
name: Di Rico, G.
name: Dultzin, D.
name: Fuhrmann, L.
name: Gomez, J. L.
name: Gurwell, M. A.
name: Jorstad, S. G.
name: Heidt, J.
name: Hiriart, D.
name: Hsiao, H. Y.
name: Kimeridze, G.
name: Konstantinova, T. S.
name: Kopatskaya, E. N.
name: Koptelova, E.
name: Kurtanidze, O.
name: Larionov, V. M.
name: Leto, P.
name: Lindfors, E.
name: Lopez, J. M.
name: Marscher, A. P.
name: McHardy, I. M.
name: Melnichuk, D. A.
name: Mommert, M.
name: Mujica, R.
name: Nilsson, K.
name: Pasanen, M.
name: Roca-Sogorb, M.
name: Sorcia, M.
name: Takalo, L. O.
name: Taylor, B.
name: Trigilio, C.
name: Troitsky, I. S.
name: Umana, G.
name: Antonelli, L. A.
name: Colafrancesco, S.
name: Cutini, S.
name: Gasparrini, D.
name: Pittori, C.
name: Preger, B.
name: Santolamazza, P.
name: Verrecchia, F.
name: Giommi, P.
name: Salotti, L.
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report the detection by the AGILE satellite of a rapid gamma-ray flare from the powerful gamma-ray quasar PKS 1510-089, during a pointing centered on the Galactic Center region from 1 March to 30 March 2008. This source has been continuosly monitored in the radio-to-optical bands by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT). Moreover, the gamma-ray flaring episode triggered three ToO observations by the Swift satellite in three consecutive days, starting from 20 March 2008. In the period 1-16 March 2008, AGILE detected gamma-ray emission from PKS 1510-089 at a significance level of 6.2-sigma with an average flux over the entire period of (84 +/- 17) x 10^{-8} photons cm^{-2} s^{-1} for photon energies above 100 MeV. After a predefined satellite re-pointing, between 17 and 21 March 2008, AGILE detected the source at a significance level of 7.3-sigma, with an average flux (E &gt; 100 MeV) of (134 +/- 29) x 10^{-8} photons cm^{-2} s^{-1} and a peak level of (281 +/- 68) x 10^{-8} photons cm^{-2} s^{-1} with daily integration. During the observing period January-April 2008, the source also showed an intense and variable optical activity, with several flaring episodes and a significant increase of the flux was observed at millimetric frequencies. Moreover, in the X-ray band the Swift/XRT observations seem to show an harder-when-brighter behaviour of the source spectrum. The spectral energy distribution of mid-March 2008 is modelled with a homogeneous one-zone synchrotron self Compton emission plus contributions from inverse Compton scattering of external photons from both the accretion disc and the broad line region. Indeed, some features in the optical-UV spectrum seem to indicate the presence of Seyfert-like components, such as the little blue bump and the big blue bump.
description: 10 pages, 4 figures and 2 tables, accepted for publication in A&amp;A