Search for TeV gamma ray emission from the Andromeda galaxy

¹ Max Planck Institut für Kernphysik, Postfach 103980, 69029 Heidelberg, Germany
² Yerevan Physics Institute, Alikhanian Br. 2, 375036 Yerevan, Armenia 

³ Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
⁴ Universität Wuppertal, Fachbereich Physik, Gaußstr. 20, 42097 Wuppertal, Germany
⁵ Universität Kiel, Institut für Experimentelle und Angewandte Physik, Leibnizstraße 15-19, 24118 Kiel, Germany
⁶ Max Planck Institut für Physik, Föhringer Ring 6, 80805 München, Germany
⁷ Universidad Complutense, Facultad de Ciencias Físicas, Ciudad Universitaria, 28040 Madrid, Spain

Corresponding author: W. Hofmann, wh@daniel.mpi-hd.mpg.de

Received: 6 November 2002
Accepted: 23 December 2002

Abstract

Using the HEGRA system of imaging atmospheric Cherenkov telescopes, the Andromeda galaxy (M 31) was surveyed for TeV gamma ray emission. Given the large field of view of the HEGRA telescopes, three pointings were sufficient to cover all of M 31, including also M 32 and NGC 205. No indications for point sources of TeV gamma rays were found. Upper limits are given at a level of a few percent of the Crab flux. A specific search for monoenergetic gamma-ray lines from annihilation of supersymmetric dark matter particles accumulating near the center of M 31 resulted in flux limits in the 10^-13 cm^-2 s^-1 range, well above the predicted MSSM flux levels except for models with pronounced dark-matter spikes or strongly enhanced annihilation rates.