Fermi-LAT discovery of GeV gamma-ray emission from the young supernova remnant Cassiopeia A

A. A. Abdo M. Ackermann M. Ajello A. Allafort L. Baldini J. Ballet 1 G. Barbiellini M. G. Baring D. Bastieri B. M. Baughman K. Bechtol R. Bellazzini B. Berenji R. D. Blandford E. D. Bloom E. Bonamente A. W. Borgland J. Bregeon A. Brez M. Brigida P. Bruel 2 R. Buehler T. H. Burnett G. Busetto G. A. Caliandro R. A. Cameron P. A. Caraveo J. M. Casandjian 1 C. Cecchi Ö. Çelik E. Charles S. Chaty A. Chekhtman C. C. Cheung J. Chiang A. N. Cillis S. Ciprini R. Claus J. Cohen-Tanugi 3 J. Conrad S. Corbel F. De Palma S. W. Digel M. Dormody E. Do Couto E Silva P. S. Drell R. Dubois D. Dumora 4 Y. Edmonds C. Farnier 3 C. Favuzzi S. J. Fegan 2 E. C. Ferrara W. B. Focke P. Fortin 2 M. Frailis Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Gehrels S. Germani G. Giavitto N. Giglietto F. Giordano T. Glanzman G. Godfrey I. A. Grenier M.-H. Grondin 4 J. E. Grove L. Guillemot 4 S. Guiriec Y. Hanabata E. Hays A. K. Harding M. Hayashida D. Horan 2 R. E. Hughes M. S. Jackson A. S. Johnson T. J. Johnson W. N. Johnson T. Kamae H. Katagiri J. Kataoka N. Kawai M. Kerr J. Knödlseder 5 M. Kuss J. Lande L. Latronico M. Lemoine-Goumard 4 F. Longo F. Loparco B. Lott 4 M. N. Lovellette P. Lubrano A. Makeev M. N. Mazziotta C. Meurer P. F. Michelson W. Mitthumsiri T. Mizuno C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia T. Nakamori P. L. Nolan J. P. Norris E. Nuss 3 T. Ohsugi A. Okumura N. Omodei E. Orlando J. F. Ormes D. Paneque J. H. Panetta V. Pelassa 3 M. Pepe M. Pesce-Rollins F. Piron 3 M. Pohl T. A. Porter S. Rainò R. Rando A. Reimer O. Reimer T. Reposeur 4 S. Ritz A. Y. Rodriguez R. W. Romani M. Roth H. F.-W. Sadrozinski A. Sander P. M. Saz Parkinson J. D. Scargle C. Sgrò E. J. Siskind D. A. Smith 4 P. D. Smith P. Spinelli M. S. Strickman D. J. Suson H. Tajima T. Takahashi T. Tanaka J. B. Thayer J. G. Thayer D. J. Thompson S. E. Thorsett L. Tibaldo 1 O. Tibolla D. F. Torres G. Tosti A. Tramacere Y. Uchiyama T. L. Usher A. Van Etten V. Vasileiou C. Venter N. Vilchez 5 V. Vitale A. P. Waite P. Wang B. L. Winer K. S. Wood R. Yamazaki T. Ylinen M. Ziegler
Abstract : We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2$\sigma$ above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation - Cassiopeia A. The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as $W_{\mathrm{CR}} \approx (1-4) \times 10^{49}$ erg thanks to the well-known density in the remnant assuming that the observed gamma-ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B $\gt 0.1$ mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.
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Journal articles
Astrophysical Journal Letters, 2010, 710, pp.L92-L97. <10.1088/2041-8205/710/1/L92>


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A. A. Abdo, M. Ackermann, M. Ajello, A. Allafort, L. Baldini, et al.. Fermi-LAT discovery of GeV gamma-ray emission from the young supernova remnant Cassiopeia A. Astrophysical Journal Letters, 2010, 710, pp.L92-L97. <10.1088/2041-8205/710/1/L92>. <in2p3-00461069>

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