Ferma gamma-ray space telescope observations of gamma-ray outburst from 3C 454.3 in 2009 december and 2010 april

Markus Ackermann , Marco Ajello , Luca Baldini , Jean Ballet (1) , Guido Barbiellini , D. Bastieri , K. Bechtol , R. Bellazzini , B. Berenji , R. D. Blandford , E. Bonamente , A. W. Borgland , J. Bregeon , M. Brigida , Pascal Bruel (2) , R. Buehler , T. H. Burnett , S. Buson , G. A. Caliandro , R. A. Cameron , P. A. Caraveo , S. Carrigan , J. M. Casandjian (1) , E. Cavazzuti , C. Cecchi , O. Celik , A. Chekhtman , C. C. Cheung , J. Chiang , S. Ciprini , R. Claus , J. Cohen-Tanugi (3) , S. Corbel (1, 4) , S. Cutini , F. d'Ammando , C. D. Dermer , A. de Angelis , F. de Palma , S. W. Digel , E. Do Couto E Silva , P. S. Drell , R. Dubois , D. Dumora (5) , L. Escande (5) , C. Favuzzi , S. J. Fegan (2) , E. C. Ferrara , L. Fuhrmann , Y. Fukazawa , P. Fusco , F. Gargano , D. Gasparrini , N. Gehrels , S. Germani , B. Giebels (2) , N. Giglietto , P. Giommi , F. Giordano , M. Giroletti , T. Glanzman , G. Godfrey , I. A. Grenier (1) , J. E. Grove , S. Guiriec , D. Hadasch , M. Hayashida , E. Hays , G. Johannesson , A. S. Johnson , W. N. Johnson , T. Kamae , H. Katagiri , J. Kataoka , Jürgen Knödlseder (6) , M. Kuss , J. Lande , S. Larsson , L. Latronico , S.-H. Lee , M. Llena Garde , F. Longo , F. Loparco , B. Lott (5) , P. Lubrano , G. M. Madejski , A. Makeev , N. Marchili , M. N. Mazziotta , J. E. Mcenery , J. Mehault (3) , P. F. Michelson , T. Mizuno , C. Monte , M. E. Monzani , A. Morselli , I. V. Moskalenko , S. Murgia , T. Nakamori , K. Nalewajko , M. Naumann-Godo , P. L. Nolan , J. P. Norris , E. Nuss (3) , T. Ohsugi , A. Okumura , N. Omodei , E. Orlando , J. F. Ormes , V. Pelassa (3) , M. Pepe , M. Pesce-Rollins , F. Piron (3) , T.A. Porter , S. Raino , R. Rando , M. Razzano , A. Reimer , O. Reimer , L. C. Reyes , J. Ripken , S. Ritz , M. Roth , H. F.-W. Sadrozinski , D. Sanchez (2) , A. Sander , J. D. Scargle , C. Sgro , M. Sikora , E. J. Siskind , G. Spandre , P. Spinelli , M. S. Strickman , D. J. Suson , H. Takahashi , T. Takahashi , T. Tanaka , Y. Tanaka , J. B. Thayer , J. G. Thayer , D. J. Thompson , L. Tibaldo (1) , D. F. Torres , G. Tosti , A. Tramacere , T. L. Usher , J. Vandenbroucke , N. Vilchez (6) , V. Vitale , A. P. Waite , P. Wang , A. E. Wehrle , B. L. Winer , Z. Yang , T. Ylinen , M. Ziegler

1 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
2 LLR - Laboratoire Leprince-Ringuet
3 LPTA - Laboratoire de Physique Théorique et Astroparticules
4 IUF - Institut universitaire de France
5 CENBG - Centre d'Etudes Nucléaires de Bordeaux Gradignan
6 CESR - Centre d'étude spatiale des rayonnements

The flat spectrum radio quasar 3C 454.3 underwent an extraordinary outburst in 2009 December when it became the brightest γ-ray source in the sky for over 1 week. Its daily flux measured with the Fermi-Large Area Telescope at photon energies E>100 MeV reached F 100 = 22 ± 1 × 10–6 photon cm–2 s–1, representing the highest daily flux of any blazar ever recorded in high-energy γ-rays. It again became the brightest source in the sky in 2010 April, triggering a pointed-mode observation by Fermi. The correlated γ-ray temporal and spectral properties during these exceptional events are presented and discussed. The main results show flux variability over time scales less than 3 hr and very mild spectral variability with an indication of gradual hardening preceding major flares. The light curves during periods of enhanced activity in 2008 July-August and 2010 December show strong resemblance, with a flux plateau of a few days preceding the major flare. No consistent loop pattern emerged in the γ-ray spectral index versus the flux plane as would be expected in acceleration and cooling scenarios. The maximum energy of a photon from 3C 454.3 is ≈20 GeV and a minimum Doppler factor of ≈13 is derived. The γ-ray spectrum of 3C 454.3 shows a significant spectral break between ≈2 and 3 GeV that is very weakly dependent on the flux state, even when the flux changes by an order of magnitude.

Mots clés: galaxies: active; gamma rays: galaxies; quasars: individual (3C 454.3)

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Phénomènes cosmiques de haute energie [astro-ph.HE]

Markus Ackermann, Marco Ajello, Luca Baldini, Jean Ballet, Guido Barbiellini, et al.. Ferma gamma-ray space telescope observations of gamma-ray outburst from 3C 454.3 in 2009 december and 2010 april. The Astrophysical Journal, 2010, 721, pp.1383-1396. ⟨10.1088/0004-637X/721/2/1383⟩. ⟨in2p3-00530295⟩