Fermi Large Area Telescope Gamma-Ray Detection of the Radio Galaxy M87

A. A. Abdo M. Ackermann M. Ajello W. B. Atwood M. Axelsson L. Baldini J. Ballet 1 G. Barbiellini D. Bastieri 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 T.H. Burnett G.A. Caliandro R.A. Cameron A. Cannon P.A. Caraveo J.M. Casandjian 1 E. Cavazzuti C. Cecchi O. Celik E. Charles C.C. Cheung J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi 3 S. Colafrancesco J. Conrad L. Costamante S. Cutini D.S. Davis C.D. Dermer A. De Angelis F. De Palma S.W. Digel D. Donato E. Do Couto E Silva P.S. Drell R. Dubois D. Dumora 4 Y. Edmonds C. Farnier 3 C. Favuzzi S.J. Fegan 2 J. Finke W.B. Focke P. Fortin 2 M. Frailis Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Gehrels M. Georganopoulos S. Germani B. Giebels 2 N. Giglietto P. Giommi F. Giordano M. Giroletti T. Glanzman G. Godfrey I.A. Grenier 1 M.H. Grondin 4 J.E. Grove L. Guillemot 4 S. Guiriec 3 Y. Hanabata A.K. Harding M. Hayashida E. Hays D. Horan 2 G. Jóhannesson A.S. Johnson R.P. Johnson T.J. Johnson W.N. Johnson T. Kamae H. Katagiri J. Kataoka N. Kawai M. Kerr J. Knödlseder 5 M. L. Kocian M. Kuss J. Lande L. Latronico M. Lemoine-Goumard 4 F. Longo F. Loparco B. Lott 4 M.N. Lovellette P. Lubrano G.M. Madjeski A. Makeev M.N. Mazziotta W. Mcconville J.E. Mcenery C. Meurer P.F. Michelson W. Mitthumsiri T. Mizuno A.A. Moiseev C. Monte M.E. Monzani A. Morselli I.V. Moskalenko S. Murgia P.L. Nolan J. P. Norris E. Nuss 3 T. Ohsugi N. Omodei E. Orlando J.F. Ormes M. Ozaki D. Paneque J.H. Panetta D. Parent 4 V. Pelassa 3 M. Pepe M. Pesce-Rollins F. Piron 3 T.A. Porter S. Rainò R. Rando M. Razzano A. Reimer T. Reposeur 4 S. Ritz L.S. Rochester A. Y. Rodriguez R.W. Romani F. Ryde H. F.-W. Sadrozinski R. Sambruna D. Sanchez 2 P.M. Saz Parkinson J.D. Scargle C. Sgrò M. Shaw D. A. Smith 4 P. D. Smith G. Spandre P. Spinelli M.S. Strickman D.J. Suson H. Tajima H. Takahashi T. Tanaka G.B. Taylor J.B. Thayer D.J. Thompson L. Tibaldo 1 D.F. Torres G. Tosti A. Tramacere Y. Uchiyama T.L. Usher V. Vasileiou N. Vilchez 5 A. P. Waite P. Wang B. L. Winer K. S. Wood T. Ylinen M. Ziegler D.E. Harris F. Massaro L. Stawarz
Abstract : We report the Fermi-LAT discovery of high-energy (MeV/GeV) gamma-ray emission positionally consistent with the center of the radio galaxy M87, at a source significance of over 10 sigma in ten-months of all-sky survey data. Following the detections of Cen A and Per A, this makes M87 the third radio galaxy seen with the LAT. The faint point-like gamma-ray source has a >100 MeV flux of 2.45 (+/- 0.63) x 10^-8 ph cm^-2 s^-1 (photon index = 2.26 +/- 0.13) with no significant variability detected within the LAT observation. This flux is comparable with the previous EGRET upper limit (< 2.18 x 10^-8 ph cm^-2 s^-1, 2 sigma), thus there is no evidence for a significant MeV/GeV flare on decade timescales. Contemporaneous Chandra and VLBA data indicate low activity in the unresolved X-ray and radio core relative to previous observations, suggesting M87 is in a quiescent overall level over the first year of Fermi-LAT observations. The LAT gamma-ray spectrum is modeled as synchrotron self-Compton (SSC) emission from the electron population producing the radio-to-X-ray emission in the core. The resultant SSC spectrum extrapolates smoothly from the LAT band to the historical-minimum TeV emission. Alternative models for the core and possible contributions from the kiloparsec-scale jet in M87 are considered, and can not be excluded.
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Journal articles
Astrophysical Journal, American Astronomical Society, 2009, 707, pp.55-60. <10.1088/0004-637X/707/1/55>


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A. A. Abdo, M. Ackermann, M. Ajello, W. B. Atwood, M. Axelsson, et al.. Fermi Large Area Telescope Gamma-Ray Detection of the Radio Galaxy M87. Astrophysical Journal, American Astronomical Society, 2009, 707, pp.55-60. <10.1088/0004-637X/707/1/55>. <in2p3-00440769>

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