Free access article



A&A 425, L13-L17 (2004)
DOI: 10.1051/0004-6361:200400055

Letter

Very high energy gamma rays from the direction of Sagittarius A ^*

F. Aharonian¹, A. G. Akhperjanian², K.-M. Aye³, A. R. Bazer-Bachi⁴, M. Beilicke⁵, W. Benbow¹, D. Berge¹, P. Berghaus⁶, K. Bernlöhr^{1, 7}, O. Bolz¹, C. Boisson⁸, C. Borgmeier⁷, F. Breitling⁷, A. M. Brown³, J. Bussons Gordo⁹, P. M. Chadwick³, V. R. Chitnis^{10, 11}, L.-M. Chounet¹², R. Cornils⁵, L. Costamante^{1, 11}, B. Degrange¹², A. Djannati-Ataï⁶, L. O'C. Drury¹³, T. Ergin⁷, P. Espigat⁶, F. Feinstein⁹, P. Fleury¹², G. Fontaine¹², S. Funk¹, Y. Gallant⁹, B. Giebels¹², S. Gillessen¹, P. Goret¹⁴, J. Guy¹⁰, C. Hadjichristidis³, M. Hauser¹⁵, G. Heinzelmann⁵, G. Henri¹⁶, G. Hermann¹, J. A. Hinton¹, W. Hofmann¹, M. Holleran¹⁷, D. Horns¹, O. C. de Jager¹⁷, I. Jung^{1, 15}, B. Khélifi¹, Nu. Komin⁷, A. Konopelko^{1, 7}, I. J. Latham³, R. Le Gallou³, M. Lemoine¹², A. Lemière⁶, N. Leroy¹², T. Lohse⁷, A. Marcowith⁴, C. Masterson^{1, 11}, T. J. L. McComb³, M. de Naurois¹⁰, S. J. Nolan³, A. Noutsos³, K. J. Orford³, J. L. Osborne³, M. Ouchrif^{10, 11}, M. Panter¹, G. Pelletier¹⁶, S. Pita⁶, M. Pohl¹⁸, G. Pühlhofer^{1, 15}, M. Punch⁶, B. C. Raubenheimer¹⁷, M. Raue⁵, J. Raux¹⁰, S. M. Rayner³, I. Redondo^{12, 11}, A. Reimer¹⁸, O. Reimer¹⁸, J. Ripken⁵, M. Rivoal¹⁰, L. Rob¹⁹, L. Rolland¹⁰, G. Rowell¹, V. Sahakian², L. Saugé¹⁶, S. Schlenker⁷, R. Schlickeiser¹⁸, C. Schuster¹⁸, U. Schwanke⁷, M. Siewert¹⁸, H. Sol⁸, R. Steenkamp²⁰, C. Stegmann⁷, J.-P. Tavernet¹⁰, C. G. Théoret⁶, M. Tluczykont^{12, 11}, D. J. van der Walt¹⁷, G. Vasileiadis⁹, P. Vincent¹⁰, B. Visser¹⁷, H. J. Völk¹ and S. J. Wagner<sup>15

1</sup>  Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
    e-mail: Jim.Hinton@mpi-hd.mpg.de
²  Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan, Armenia
³  University of Durham, Department of Physics, South Road, Durham DH1 3LE, UK
⁴  Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, 9 Av. du Colonel Roche, BP 4346, 31029 Toulouse Cedex 4, France
⁵  Universität Hamburg, Inst. für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
⁶  Physique Corpusculaire et Cosmologie, IN2P3/CNRS, Collège de France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
⁷  Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
⁸  LUTH, UMR 8102 du CNRS, Observatoire de Paris, Section de Meudon, 92195 Meudon Cedex, France
⁹  Groupe d'Astroparticules de Montpellier, IN2P3/CNRS, Université Montpellier II, CC85, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
¹⁰  Laboratoire de Physique Nucléaire et de Hautes Énergies, IN2P3/CNRS, Universités Paris VI & VII, 4 place Jussieu, 75231 Paris Cedex 05, France
¹¹  European Associated Laboratory for Gamma-Ray Astronomy, jointly supported by CNRS and MPG
¹²  Laboratoire Leprince-Ringuet, IN2P3/CNRS, École Polytechnique, 91128 Palaiseau, France
¹³  Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
¹⁴  Service d'Astrophysique, DAPNIA/DSM/CEA, CE Saclay, 91191 Gif-sur-Yvette, France
¹⁵  Landessternwarte, Königstuhl, 69117 Heidelberg, Germany
¹⁶  Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
¹⁷  Unit for Space Physics, North-West University, Potchefstroom 2520, South Africa
¹⁸  Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
¹⁹  Institute of Particle and Nuclear Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
²⁰  University of Namibia, Private Bag 13301, Windhoek, Namibia

(Received 29 June 2004 / Accepted 12 August 2004)

Abstract
We report the detection of a point-like source of very high energy (VHE) -rays coincident within  1' of Sgr A ^*, obtained with the HESS array of Cherenkov telescopes. The -rays exhibit a power-law energy spectrum with a spectral index of and a flux above the 165 GeV threshold of  m ^-2 s ^-1. The measured flux and spectrum differ substantially from recent results reported in particular by the CANGAROO collaboration.

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© ESO 2004