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Spectral Properties of Bright Fermi-detected Blazars in the Gamma-ray Band

A. A. Abdo Markus Ackermann Marco Ajello W. B. Atwood Magnus Axelsson Luca Baldini Jean Ballet 1 Guido Barbiellini D. Bastieri K. Bechtol R. Bellazzini B. Berenji R. D. Blandford E. D. Bloom E. Bonamente A. W. Borgland A. Bouvier J. Bregeon A. Brez M. Brigida Pascal Bruel 2 T. H. Burnett S. Buson G. A. Caliandro R. A. Cameron P. A. Caraveo S. Carrigan J. M. Casandjian 1 E. Cavazzuti C. Cecchi Ö. Çelik E. Charles A. Chekhtman C. C. Cheung J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi 3 J. Conrad S. Cutini C. D. Dermer A. de Angelis F. de Palma S. W. Digel E. Do Couto E Silva P. S. Drell R. Dubois D. Dumora 4 C. Farnier 3 C. Favuzzi S. J. Fegan 2 W. B. Focke P. Fortin 2 M. Frailis Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Gehrels S. Germani B. Giebels 2 N. Giglietto P. Giommi F. Giordano T. Glanzman G. Godfrey I. A. Grenier 1 M.-H. Grondin 4 J. E. Grove L. Guillemot 4 S. Guiriec A. K. Harding R. C. Hartman M. Hayashida E. Hays S. E. Healey D. Horan 2 R. E. Hughes M. S. Jackson G. Jóhannesson A. S. Johnson W. N. Johnson T. Kamae H. Katagiri J. Kataoka N. Kawai M. Kerr J. Knödlseder 5 M. Kuss J. Lande L. Latronico M. Lemoine-Goumard 4 F. Longo F. Loparco B. Lott 4 M. N. Lovellette P. Lubrano G. M. Madejski A. Makeev M. N. Mazziotta W. Mcconville J. E. Mcenery C. Meurer P. F. Michelson W. Mitthumsiri T. Mizuno A. A. Moiseev C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia P. L. Nolan J. P. Norris E. Nuss 3 T. Ohsugi N. Omodei E. Orlando J. F. Ormes D. Paneque J. H. Panetta D. Parent 4 V. Pelassa 3 M. Pepe M. Persic M. Pesce-Rollins F. Piron 3 T.A. Porter S. Rainò R. Rando M. Razzano A. Reimer O. Reimer T. Reposeur 4 S. Ritz L. S. Rochester A. Y. Rodriguez R. W. Romani M. Roth F. Ryde H. F.-W. Sadrozinski D. Sanchez 2 A. Sander P. M. Saz Parkinson J. D. Scargle C. Sgrò E. J. Siskind David Stanley Smith 4 P. D. Smith G. Spandre P. Spinelli M. S. Strickman D. J. Suson H. Tajima H. Takahashi T. Takahashi T. Tanaka J. B. Thayer J. G. Thayer D. J. Thompson L. Tibaldo 1 D. F. Torres G. Tosti A. Tramacere Y. Uchiyama T. L. Usher V. Vasileiou N. Vilchez 5 M. Villata V. Vitale A. P. Waite P. Wang B. L. Winer K. S. Wood T. Ylinen M. Ziegler
Abstract : The gamma-ray energy spectra of bright blazars of the LAT Bright AGN Sample (LBAS) are investigated using Fermi-LAT data. Spectral properties (hardness, curvature and variability) established using a data set accumulated over 6 months of operation are presented and discussed for different blazar classes and subclasses: Flat Spectrum Radio Quasars (FSRQs), Low-synchrotron peaked BLLacs (LSP-BLLacs), Intermediate-synchrotron peaked BLLacs (ISP-BLLacs) and High-synchrotron peaked BLLacs (HSP-BLLacs). The distribution of photon index (obtained from a power-law fit above 100 MeV) is found to correlate strongly with blazar subclass. The change in spectral index from that averaged over the six month observing period is < 0.2-0.3 when the flux varies by about an order of magnitude, with a tendency toward harder spectra when the flux is brighter for FSRQs and LSP-BLLacs. A strong departure from a single power-law spectrum appears to be a common feature for FSRQs. This feature is also present for some high-luminosity LSP-BLLacs, and a small number of ISP-BLLacs. It is absent in all LBAS HSP-BLLacs. For 3C 454.3 and AO 0235+164, the two brightest FSRQ source and LSP-BLLac source respectively, a broken power law gives the most acceptable of power law, broken power law, and curved forms. The consequences of these findings are discussed.
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Submitted on : Tuesday, March 2, 2010 - 3:59:22 PM
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A. A. Abdo, Markus Ackermann, Marco Ajello, W. B. Atwood, Magnus Axelsson, et al.. Spectral Properties of Bright Fermi-detected Blazars in the Gamma-ray Band. The Astrophysical Journal, American Astronomical Society, 2010, 710, pp.1271-1285. ⟨10.1088/0004-637X/710/2/1271⟩. ⟨in2p3-00460830⟩



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