A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 x 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.
Gamma-Ray Flares from the Crab Nebula / Abdo AA; Ackermann M; Ajello M; Allafort A; Baldini L; Ballet J; Barbiellini G; Bastieri D; Bechtol K; Bellazzini R; Berenji B; Blandford RD; Bloom ED; Bonamente E; Borgland AW; Bouvier A; Brandt TJ; Bregeon J; Brez A; Brigida M; Bruel P; Buehler R; Buson S; Caliandro GA; Cameron RA; Cannon A; Caraveo PA; Casandjian JM; Celik O; Charles E; Chekhtman A; Cheung CC; Chiang J; Ciprini S; Claus R; Cohen-Tanugi J; Costamante L; Cutini S; DAmmando F; Dermer CD; de Angelis A; de Luca A; de Palma F; Digel SW; Silva EDE; Drell PS; Drlica-Wagner A; Dubois R; Dumora D; Favuzzi C; Fegan SJ; Ferrara EC; Focke WB; Fortin P; Frailis M; Fukazawa Y; Funk S; Fusco P; Gargano F; Gasparrini D; Gehrels N; Germani S; Giglietto N; Giordano F; Giroletti M; Glanzman T; Godfrey G; Grenier IA; Grondin MH; Grove JE; Guiriec S; Hadasch D; Hanabata Y; Harding AK; Hayashi K; Hayashida M; Hays E; Horan D; Itoh R; Johannesson G; Johnson AS; Johnson TJ; Khangulyan D; Kamae T; Katagiri H; Kataoka J; Kerr M; Knodlseder J; Kuss M; Lande J; Latronico L; Lee SH; Lemoine-Goumard M; Longo F; Loparco F; Lubrano P; Madejski GM; Makeev A; Marelli M; Mazziotta MN; McEnery JE; Michelson PF; Mitthumsiri W; Mizuno T; Moiseev AA; Monte C; Monzani ME; Morselli A; Moskalenko IV; Murgia S; Nakamori T; Naumann-Godo M; Nolan PL; Norris JP; Nuss E; Ohsugi T; Okumura A; Omodei N; Ormes JF; Ozaki M; Paneque D; Parent D; Pelassa V; Pepe M; Pesce-Rollins M; Pierbattista M; Piron F; Porter TA; Raino S; Rando R; Ray PS; Razzano M; Reimer A; Reimer O; Reposeur T; Ritz S; Romani RW; Sadrozinski HFW; Sanchez D; Parkinson PMS; Scargle JD; Schalk TL; Sgro C; Siskind EJ; Smith PD; Spandre G; Spinelli P; Strickman MS; Suson DJ; Takahashi H; Takahashi T; Tanaka T; Thayer JB; Thompson DJ; Tibaldo L; Torres DF; Tosti G; Tramacere A; Troja E; Uchiyama Y; Vandenbroucke J; Vasileiou V; Vianello G; Vitale V; Wang P; Wood KS; Yang Z; Ziegler M. - In: SCIENCE. - ISSN 0036-8075. - STAMPA. - 331:6018(2011), pp. 739-742. [10.1126/science.1199705]
Gamma-Ray Flares from the Crab Nebula
D'AMMANDO, FILIPPO;
2011
Abstract
A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 x 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
