AGILE detection of extreme γ -ray activity from the blazar PKS 1510-089 during March 2009: Multifrequency analysis
Journal
Date Issued
2011
Author(s)
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Pucella, G.
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Krimm, H.A.
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Donnarumma, I.
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Barbiellini, G.
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Boffelli, F.
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Cattaneo, P.W.
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Chen, A.W.
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Cocco, V.
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Di Cocco, G.
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Ferrari, A.
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Froysland, T.
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Frutti, M.
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Galli, M.
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Lapshov, I.
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Lipari, P.
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Longo, F.
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Morselli, A.
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Perotti, F.
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Picozza, P.
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Porrovecchio, G.
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Prest, M.
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Rapisarda, M.
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Rappoldi, A.
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Rubini, A.
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Sabatini, S.
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Striani, E.
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Vallazza, E.
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Zambra, A.
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Zanello, D.
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Agudo, I.
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Aller, H.D.
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Aller, M.F.
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Arkharov, A.A.
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Bach, U.
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Benitez, E.
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Berdyugin, A.
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Blinov, D.A.
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Chen, W.P.
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Forné, E.
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Fuhrmann, L.
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Gómez, J.L.
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Gurwell, M.A.
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Jordan, B.
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Jorstad, S.G.
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Heidt, J.
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Hiriart, D.
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Hovatta, T.
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Hsiao, H.Y.
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Kimeridze, G.
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Konstantinova, T.S.
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Kopatskaya, E.N.
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Koptelova, E.
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Kurtanidze, O.M.
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Kurtanidze, S.O.
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Larionov, V.M.
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Lähteenmäki, A.
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Lindfors, E.
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Marscher, A.P.
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McBreen, B.
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McHardy, I.M.
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Morozova, D.A.
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Nilsson, K.
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Pasanen, M.
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Roca-Sogorb, M.
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Sillanpää, A.
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Takalo, L.O.
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Tornikoski, M.
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Troitsky, I.S.
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Colafrancesco, S.
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Santolamazza, P.
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Giommi, P.
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Salotti, L.
Abstract
We report on the extreme gamma-ray activity from the FSRQ PKS 1510-089
observed by AGILE in March 2009. In the same period a radio-to-optical
monitoring of the source was provided by the GASP-WEBT and REM. Moreover,
several Swift ToO observations were triggered, adding important information on
the source behaviour from optical/UV to hard X-rays. We paid particular
attention to the calibration of the Swift/UVOT data to make it suitable to the
blazars spectra. Simultaneous observations from radio to gamma rays allowed us
to study in detail the correlation among the emission variability at different
frequencies and to investigate the mechanisms at work. In the period 9-30 March
2009, AGILE detected an average gamma-ray flux of (311+/-21)x10^-8 ph cm^-2
s^-1 for E>100 MeV, and a peak level of (702+/-131)x10^-8 ph cm^-2 s^-1 on
daily integration. The gamma-ray activity occurred during a period of
increasing activity from near-IR to UV, with a flaring episode detected on
26-27 March 2009, suggesting that a single mechanism is responsible for the
flux enhancement observed from near-IR to UV. By contrast, Swift/XRT
observations seem to show no clear correlation of the X-ray fluxes with the
optical and gamma-ray ones. However, the X-ray observations show a harder
photon index (1.3-1.6) with respect to most FSRQs and a hint of
harder-when-brighter behaviour, indicating the possible presence of a second
emission component at soft X-ray energies. Moreover, the broad band spectrum
from radio-to-UV confirmed the evidence of thermal features in the optical/UV
spectrum of PKS 1510-089 also during high gamma-ray state. On the other hand,
during 25-26 March 2009 a flat spectrum in the optical/UV energy band was
observed, suggesting an important contribution of the synchrotron emission in
this part of the spectrum during the brightest gamma-ray flare, therefore a
significant shift of the synchrotron peak.
Volume
529
Start page
A145
Issn Identifier
0004-6361
Ads BibCode
2011A&A...529A.145D
Rights
open.access
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