Observation of VHE γ-rays from Cassiopeia A with the MAGIC telescope

¹ Universität Würzburg, 97074 Würzburg, Germany
² Institut de Física d'Altes Energies, Edifici Cn., 08193 Bellaterra (Barcelona), Spain e-mail: emma@apc.univ-paris7.fr
³ ETH Zurich, 8093, Switzerland
⁴ Universidad Complutense, 28040 Madrid, Spain
⁵ Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
⁶ Max-Planck-Institut für Physik, 80805 München, Germany
⁷ Università di Padova and INFN, 35131 Padova, Italy
⁸ Universität Dortmund, 44227 Dortmund, Germany
⁹ University of Łódź, 90236 Lodz, Poland
¹⁰ Universitat de Barcelona, 08028 Barcelona, Spain
¹¹ Yerevan Physics Institute, 375036 Yerevan, Armenia
¹² Instituto de Astrofisica de Canarias, 38200 La Laguna, Tenerife, Spain
¹³ Università di Udine, and INFN Trieste, 33100 Udine, Italy
¹⁴ Università di Siena, and INFN Pisa, 53100 Siena, Italy
¹⁵ University of California, Davis, 95616-8677, USA
¹⁶ Humboldt-Universität zu Berlin, 12489 Berlin, Germany
¹⁷ Tuorla Observatory, Turku University, 21500 Piikkiö, Finland
¹⁸ Institute for Nuclear Research and Nuclear Energy, 1784 Sofia, Bulgaria
¹⁹ INAF - Osservatorio Astronomico and INFN Trieste, 34131 Trieste, Italy
²⁰ Università di Pisa, and INFN Pisa, 56126 Pisa, Italy
²¹ ICREA and Institut de Cienciès de l'Espai (IEEC-CSIC), 08193 Bellaterra, Spain

Received: 27 June 2007
Accepted: 28 August 2007

Abstract

Aims.We searched for very high energy (VHE) γ-ray emission from the supernova remnant Cassiopeia A

Methods.The shell-type supernova remnant Cassiopeia A was observed with the 17 m MAGIC telescope between July 2006 and January 2007 for a total time of 47 h.

Results.The source was detected above an energy of 250 GeV with a significance of 5.2σ and a photon flux above 1 TeV of (7.3 ±  ±   10^-13 cm^-2s^-1. The photon spectrum is compatible with a power law dN/dE  with a photon index Γ = 2.3 ±  ± . The source is point-like within the angular resolution of the telescope.