ALBERT

Description: 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abdo, A A -- Ackermann, M -- Ajello, M -- Allafort, A -- Baldini, L -- Ballet, J -- Barbiellini, G -- Bastieri, D -- Bechtol, K -- Bellazzini, R -- Berenji, B -- Blandford, R D -- Bloom, E D -- Bonamente, E -- Borgland, A W -- Bouvier, A -- Brandt, T J -- Bregeon, J -- Brez, A -- Brigida, M -- Bruel, P -- Buehler, R -- Buson, S -- Caliandro, G A -- Cameron, R A -- Cannon, A -- Caraveo, P A -- Casandjian, J M -- Celik, O -- Charles, E -- Chekhtman, A -- Cheung, C C -- Chiang, J -- Ciprini, S -- Claus, R -- Cohen-Tanugi, J -- Costamante, L -- Cutini, S -- D'Ammando, F -- Dermer, C D -- de Angelis, A -- de Luca, A -- de Palma, F -- Digel, S W -- do Couto e Silva, E -- Drell, P S -- Drlica-Wagner, A -- Dubois, R -- Dumora, D -- Favuzzi, C -- Fegan, S J -- Ferrara, E C -- Focke, W B -- 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, I A -- Grondin, M-H -- Grove, J E -- Guiriec, S -- Hadasch, D -- Hanabata, Y -- Harding, A K -- Hayashi, K -- Hayashida, M -- Hays, E -- Horan, D -- Itoh, R -- Johannesson, G -- Johnson, A S -- Johnson, T J -- Khangulyan, D -- Kamae, T -- Katagiri, H -- Kataoka, J -- Kerr, M -- Knodlseder, J -- Kuss, M -- Lande, J -- Latronico, L -- Lee, S-H -- Lemoine-Goumard, M -- Longo, F -- Loparco, F -- Lubrano, P -- Madejski, G M -- Makeev, A -- Marelli, M -- Mazziotta, M N -- McEnery, J E -- Michelson, P F -- Mitthumsiri, W -- Mizuno, T -- Moiseev, A A -- Monte, C -- Monzani, M E -- Morselli, A -- Moskalenko, I V -- Murgia, S -- Nakamori, T -- Naumann-Godo, M -- Nolan, P L -- Norris, J P -- Nuss, E -- Ohsugi, T -- Okumura, A -- Omodei, N -- Ormes, J F -- Ozaki, M -- Paneque, D -- Parent, D -- Pelassa, V -- Pepe, M -- Pesce-Rollins, M -- Pierbattista, M -- Piron, F -- Porter, T A -- Raino, S -- Rando, R -- Ray, P S -- Razzano, M -- Reimer, A -- Reimer, O -- Reposeur, T -- Ritz, S -- Romani, R W -- Sadrozinski, H F-W -- Sanchez, D -- Saz Parkinson, P M -- Scargle, J D -- Schalk, T L -- Sgro, C -- Siskind, E J -- Smith, P D -- Spandre, G -- Spinelli, P -- Strickman, M S -- Suson, D J -- Takahashi, H -- Takahashi, T -- Tanaka, T -- Thayer, J B -- Thompson, D J -- Tibaldo, L -- Torres, D F -- Tosti, G -- Tramacere, A -- Troja, E -- Uchiyama, Y -- Vandenbroucke, J -- Vasileiou, V -- Vianello, G -- Vitale, V -- Wang, P -- Wood, K S -- Yang, Z -- Ziegler, M -- New York, N.Y. -- Science. 2011 Feb 11;331(6018):739-42. doi: 10.1126/science.1199705. Epub 2011 Jan 6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21212321" target="_blank"〉PubMed〈/a〉