SPECTRAL PROPERTIES OF BRIGHT FERMI-DETECTED BLAZARS IN THE GAMMA-RAY BAND

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 (Γ, 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 6 months 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 (BPL) gives the most acceptable of power law, BPL, and curved forms. The consequences of these findings are discussed.

D. Thompson | J. Chiang | J. Grove | R. Hughes | M. Frailis | A. Moiseev | J. Scargle | N. Gehrels | M. Razzano | R. Blandford | K. Bechtol | M. Ackermann | P. Giommi | S. Digel | A. Morselli | V. Vitale | N. Kawai | T. Ohsugi | B. Lott | R. Romani | P. Drell | G. Barbiellini | A. Angelis | H. Sadrozinski | B. Winer | J. Mcenery | N. Giglietto | P. Spinelli | R. Bellazzini | A. Brez | J. Ormes | C. Cecchi | K. Wood | T. Kamae | P. Bruel | M. Roth | D. Paneque | S. Ciprini | D. Gasparrini | N. Omodei | M. Villata | Y. Fukazawa | T. Mizuno | G. Tosti | F. Longo | J. Ballet | A. Sander | T. Burnett | W. Mcconville | E. Bloom | G. Godfrey | E. Bonamente | L. Latronico | G. Spandre | A. Chekhtman | P. Lubrano | A. Borgland | J. Panetta | R. Claus | T. Glanzman | S. Fegan | D. Horan | J. Kataoka | I. Grenier | P. Caraveo | A. Bouvier | S. Murgia | J. Cohen-Tanugi | J. Thayer | J. Thayer | F. Palma | W. Atwood | C. Dermer | C. Farnier | M. Pepe | M. Axelsson | G. Madejski | H. Tajima | Tadayuki Takahashi | Takaaki Tanaka | Y. Uchiyama | A. Johnson | A. Waite | M. Ziegler | E. Silva | S. Funk | L. Guillemot | S. Ritz | R. Rando | M. Ajello | D. Bastieri | S. Buson | R. Cameron | R. Dubois | W. Focke | B. Giebels | M. Hayashida | J. Knödlseder | J. Lande | V. Pelassa | M. Persic | O. Reimer | F. Ryde | L. Tibaldo | D. Torres | T. Usher | A. Harding | L. Baldini | J. Bregeon | M. Jackson | M. Kuss | C. Sgro’ | M. Strickman | E. Cavazzuti | S. Guiriec | S. Cutini | M. Brigida | G. Caliandro | C. Favuzzi | F. Gargano | S. Germani | F. Giordano | F. Loparco | M. Mazziotta | C. Monte | M. Pesce-Rollins | S. Rainó | F. Piron | R. Hartman | P. Nolan | P. Michelson | M. Kerr | M. Lemoine-Goumard | P. Fortin | O. Celik | A. Abdo | D. Parent | P. Parkinson | J. Casandjian | B. Berenji | E. Charles | P. Fusco | E. Hays | G. Jóhannesson | M. Lovellette | W. Mitthumsiri | I. Moskalenko | E. Nuss | E. Orlando | T. Porter | T. Reposeur | E. Siskind | D. Suson | M. Grondin | V. Vasileiou | M. Monzani | S. Carrigan | D. Dumora | W. Johnson | A. Makeev | J. Norris | D. Smith | P. Smith | A. Tramacere | N. Vilchez | Pengfei Wang | T. Ylinen | L. Rochester | C. Meurer | C. C. Cheung | H. Katagiri | D. Sanchez | A. Y. Rodríguez | S. Healey | A. Reimer | J. Conrad | H. Takahashi | A. Y. Rodríguez | A. Rodríguez | M. Roth | W. Johnson

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