The flat spectrum radio quasar 3C 454.3 underwent an extraordinary outburst in 2009 December when it became the brightest gamma-ray source in the sky for over 1 week. Its daily flux measured with the Fermi-Large Area Telescope at photon energiesE > 100 MeV reached F-100 = 22 +/- 1 x 10(6) photon cm(-2) s(-1), representing the highest daily flux of any blazar ever recorded in high-energy. -rays. It again became the brightest source in the sky in 2010 April, triggering a pointed-mode observation by Fermi. The correlated. -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. -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 approximate to 20 GeV and a minimum Doppler factor of approximate to 13 is derived. The gamma-ray spectrum of 3C 454.3 shows a significant spectral break between approximate to 2 and 3 GeV that is very weakly dependent on the flux state, even when the flux changes by an order of magnitude.
Fermi Gamma-Ray Space Telescope Observations Of Gamma-Ray Outbursts From 3c 454.3 In 2009 December And 2010 April / Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Celik, O.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen Tanugi, J.; Corbel, S.; Cutini, S.; D'Ammando, F.; Dermer, C. D.; Angelis, A. d.; Palma, F. d.; Digel, S. W.; Silva, E. D. E.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Fuhrmann, L.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Johannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knodlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lee, S. H.; Garde, M. L.; Longo, Francesco; Loparco, F.; Lott, B.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marchili, N.; Mazziotta, M. N.; Mcenery, J. E.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nalewajko, K.; Naumann Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Pelassa, V.; Pepe, M.; Pesce Rollins, M.; Piron, F.; Porter, T. A.; Raino, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reyes, L. C.; Ripken, J.; Ritz, S.; Roth, M.; Sadrozinski, H. F. W.; Sanchez, D.; Sander, A.; Scargle, J. D.; Sgro, C.; Sikora, M.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Tanaka, Y.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Usher, T. L.; Vandenbroucke, J.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Yang, Z.; Ylinen, T.; Ziegler, M.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 721:(2010), pp. 1383-1396. [10.1088/0004-637X/721/2/1383]
Fermi Gamma-Ray Space Telescope Observations Of Gamma-Ray Outbursts From 3c 454.3 In 2009 December And 2010 April
LONGO, FRANCESCO;E. Orlando;
2010-01-01
Abstract
The flat spectrum radio quasar 3C 454.3 underwent an extraordinary outburst in 2009 December when it became the brightest gamma-ray source in the sky for over 1 week. Its daily flux measured with the Fermi-Large Area Telescope at photon energiesE > 100 MeV reached F-100 = 22 +/- 1 x 10(6) photon cm(-2) s(-1), representing the highest daily flux of any blazar ever recorded in high-energy. -rays. It again became the brightest source in the sky in 2010 April, triggering a pointed-mode observation by Fermi. The correlated. -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. -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 approximate to 20 GeV and a minimum Doppler factor of approximate to 13 is derived. The gamma-ray spectrum of 3C 454.3 shows a significant spectral break between approximate to 2 and 3 GeV that is very weakly dependent on the flux state, even when the flux changes by an order of magnitude.Pubblicazioni consigliate
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