Discovery of very high energy gamma-ray emission from Centaurus A with H.E.S.S.

F. Aharonian , A.G. Akhperjanian , G. Anton , U. Barres de Almeida , A.R. Bazer-Bachi (1) , Y. Becherini (2) , B. Behera , W. Benbow , K. Bernlöhr , C. Boisson (3) , A. Bochow , V. Borrel (1) , E. Brion (4) , J. Brucker , P. Brun (4) , R. Bühler , T. Bulik , I. Büsching , T. Boutelier (5) , P.M. Chadwick , A. Charbonnier (6) , R.C.G. Chaves , A. Cheesebrough , L.-M. Chounet (7) , A.C. Clapson , G. Coignet (8) , M. Dalton , M.K. Daniel , I.D. Davids , B. Degrange (7) , C. Deil , H.J. Dickinson , A. Djannati-Ataï (9) , W. Domainko , L.O'C. Drury , F. Dubois (8) , G. Dubus (5) , J. Dyks , M. Dyrda , K. Egberts , D. Emmanoulopoulos , P. Espigat (2) , C. Farnier (10) , F. Feinstein (10) , A. Fiasson (10) , A. Förster , G. Fontaine (7) , M. Füssling , S. Gabici , Y.A. Gallant (10) , L. Gérard (2) , B. Giebels (7) , J.F. Glicenstein (4) , B. Glück , P. Goret (4) , D. Göhring , D. Hauser , M. Hauser , S. Heinz , G. Heinzelmann , G. Henri (5) , G. Hermann , J.A. Hinton , A. Hoffmann , W. Hofmann , M. Holleran , S. Hoppe , D. Horns , A. Jacholkowska (6) , O.C. de Jager , C. Jahn I. Jung , K. Katarzy'Nski , U. Katz , S. Kaufmann , E. Kendziorra , M. Kerschhaggl , D. Khangulyan , B. Khélifi (7) , D. Keogh , W. Klu'Zniak , T. Kneiske , Nu. Komin (4) , K. Kosack , G. Lamanna (8) , I.J. Latham , J.-P. Lenain (3) , T. Lohse , V. Marandon (2) , J.M. Martin (3) , O. Martineau-Huynh (6) , A. Marcowith (10) , D. Maurin (6) , T.J.L. Mccomb , M.C. Medina (3) , R. Moderski , Emmanuel Moulin (4) , M. Naumann-Godo (7) , M. de Naurois (6) , D. Nedbal , D. Nekrassov , J. Niemiec , S.J. Nolan , S. Ohm , J.-F. Olive (1) , E. de Oña Wilhelmi (2) , K.J. Orford , M. Ostrowski , M. Panter , M. Paz Arribas , G. Pedaletti , G. Pelletier (5) , P.-O. Petrucci (5) , S. Pita (2) , G. Pühlhofer , M. Punch (2) , A. Quirrenbach , B.C. Raubenheimer , M. Raue , S.M. Rayner , M. Renaud (2) , F. Rieger , J. Ripken , L. Rob , S. Rosier-Lees (8) , G. Rowell , B. Rudak , C.B. Rulten , J. Ruppel , V. Sahakian , A. Santangelo , R. Schlickeiser , F.M. Schöck , R. Schröder , U. Schwanke , S. Schwarzburg , S. Schwemmer , A. Shalchi , M. Sikora , J.L. Skilton , H. Sol (3) , D. Spangler , Ł. Stawarz , R. Steenkamp , C. Stegmann , G. Superina (7) , A. Szostek (5) , P.H. Tam , J.-P. Tavernet (6) , R. Terrier (9) , O. Tibolla , M. Tluczykont , C. van Eldik , G. Vasileiadis (10) , C. Venter , L. Venter (3) , J.P. Vialle (8) , P. Vincent (6) , J. Vink , M. Vivier (4) , H.J. Völk , F. Volpe (7) , S.J. Wagner , M. Ward , A.A. Zdziarski , A. Zech (3)

1 CESR - Centre d'étude spatiale des rayonnements
2 APC (UMR_7164) - AstroParticule et Cosmologie
3 LUTH (UMR_8102) - Laboratoire Univers et Théories
4 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
5 LAOG - Laboratoire d'Astrophysique de Grenoble
6 LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
7 LLR - Laboratoire Leprince-Ringuet
8 LAPP - Laboratoire d'Annecy de Physique des Particules
9 APC - AHE - APC - Astrophysique des Hautes Energies
10 LPTA - Laboratoire de Physique Théorique et Astroparticules

We report the discovery of faint very high energy (VHE, E>100 GeV) gamma-ray emission from the radio galaxy Centaurus A in observations performed with the H.E.S.S. experiment, an imaging atmospheric Cherenkov telescope array consisting of four telescopes located in Namibia. Centaurus A has been observed for more than 120 h. A signal with a statistical significance of 5.0 sigma is detected from the region including the radio core and the inner kpc jets. The integral flux above an energy threshold of ~250 GeV is measured to be ~0.8 % of the flux of the Crab Nebula (apparent luminosity: L(>250 GeV)~2.6x10^39 erg s^-1, adopting a distance of 3.8 Mpc. The spectrum can be described by a power law with a photon index of 2.7 +/- 0.5_stat +/- 0.2_sys. No significant flux variability is detected in the data set. However, the low flux only allows detection of variability on the timescale of days to flux increments above a factor of ~15-20 (3 sigma and 4 sigma, respectively). The discovery of VHE gamma-ray emission from Centaurus A reveals particle acceleration in the source to >TeV energies and, together with M 87, establishes radio galaxies as a class of VHE emitters.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]

F. Aharonian, A.G. Akhperjanian, G. Anton, U. Barres de Almeida, A.R. Bazer-Bachi, et al.. Discovery of very high energy gamma-ray emission from Centaurus A with H.E.S.S.. The Astrophysical journal letters, 2009, 695, pp.L40-L44. ⟨10.1088/0004-637X/695/1/L40⟩. ⟨in2p3-00367126⟩