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 RD; Bonamente E; Borgland AW; Bregeon J; Brigida M; Bruel P; Buehler R; Burnett TH; Buson S; Caliandro GA; Cameron RA; Caraveo PA; Carrigan S; Casandjian JM; Cavazzuti E; Cecchi C; Celik O; Chekhtman A; Cheung CC; Chiang J; Ciprini S; Claus R; Cohen-Tanugi J; Corbel S; Cutini S; DAmmando F; Dermer CD; de Angelis A; de Palma F; Digel SW; Silva EDE; Drell PS; Dubois R; Dumora D; Escande L; Favuzzi C; Fegan SJ; Ferrara EC; 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 IA; Grove JE; Guiriec S; Hadasch D; Hayashida M; Hays E; Johannesson G; Johnson AS; Johnson WN; Kamae T; Katagiri H; Kataoka J; Knodlseder J; Kuss M; Lande J; Larsson S; Latronico L; Lee SH; Garde ML; Longo F; Loparco F; Lott B; Lubrano P; Madejski GM; Makeev A; Marchili N; Mazziotta MN; McEnery JE; Mehault J; Michelson PF; Mizuno T; Monte C; Monzani ME; Morselli A; Moskalenko IV; Murgia S; Nakamori T; Nalewajko K; Naumann-Godo M; Nolan PL; Norris JP; Nuss E; Ohsugi T; Okumura A; Omodei N; Orlando E; Ormes JF; Pelassa V; Pepe M; Pesce-Rollins M; Piron F; Porter TA; Raino S; Rando R; Razzano M; Reimer A; Reimer O; Reyes LC; Ripken J; Ritz S; Roth M; Sadrozinski HFW; Sanchez D; Sander A; Scargle JD; Sgro C; Sikora M; Siskind EJ; Spandre G; Spinelli P; Strickman MS; Suson DJ; Takahashi H; Takahashi T; Tanaka T; Tanaka Y; Thayer JB; Thayer JG; Thompson DJ; Tibaldo L; Torres DF; Tosti G; Tramacere A; Usher TL; Vandenbroucke J; Vilchez N; Vitale V; Waite AP; Wang P; Wehrle AE; Winer BL; Yang Z; Ylinen T; Ziegler M. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 721:2(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
D'AMMANDO, FILIPPO;
2010
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
