Letter to the Editor

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

¹ 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) γ-rays coincident within  of Sgr A^*, obtained with the HESS array of Cherenkov telescopes. The γ-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.