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Issue A&A Volume 396, Number 1, December II 2002 Page(s) L1 - L4 Section Letters DOI 10.1051/0004-6361:20021565

A&A 396, L1-L4 (2002)
DOI: 10.1051/0004-6361:20021565

Letter

Detection of diffuse TeV gamma-ray emission from the neaby starburst galaxy NGC 253

C. Itoh¹, R. Enomoto², S. Yanagita¹, T. Yoshida¹, A. Asahara³, G. V. Bicknell⁴, R. W. Clay⁵, P. G. Edwards⁶, S. Gunji⁷, S. Hara^{3, 8}, T. Hara⁹, T. Hattori¹⁰, Shin. Hayashi¹¹, Sei. Hayashi¹¹, S. Kabuki², F. Kajino¹¹, H. Katagiri², A. Kawachi², T. Kifune¹², H. Kubo³, J. Kushida^{3, 8}, Y. Matsubara¹³, Y. Mizumoto¹⁴, M. Mori², H. Moro¹⁰, H. Muraishi¹⁵, Y. Muraki¹³, T. Naito⁹, T. Nakase¹⁰, D. Nishida³, K. Nishijima¹⁰, K. Okumura², M. Ohishi², J. R. Patterson⁵, R. J. Protheroe⁵, K. Sakurazawa⁸, D. L. Swaby⁵, T. Tanimori³, F. Tokanai⁷, K. Tsuchiya², H. Tsunoo², T. Uchida², A. Watanabe⁷, S. Watanabe³ and T. Yoshikoshi<sup>16

1</sup>  Faculty of Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
²  Institute for Cosmic Ray Research, Univ. of Tokyo, Kashiwa, Chiba 277-8582, Japan
³  Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
⁴  MSSSO, Australian National University, ACT 2611, Australia
⁵  Department of Physics and Math. Physics, University of Adelaide, SA 5005, Australia
⁶  Institute for Space and Aeronautical Science, Sagamihara, Kanagawa 229-8510, Japan
⁷  Department of Physics, Yamagata University, Yamagata, Yamagata 990-8560, Japan
⁸  Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
⁹  Faculty of Management Information, Yamanashi Gakuin University, Kofu,Yamanashi 400-8575, Japan
¹⁰  Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
¹¹  Department of Physics, Konan University, Hyogo 658-8501, Japan
¹²  Faculty of Engineering, Shinshu University, Nagano, Nagano 380-8553, Japan
¹³  STE Laboratory, Nagoya University, Nagoya, Aichi 464-8601, Japan
¹⁴  National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
¹⁵  Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki 300-0394, Japan
¹⁶  Department of Physics, Osaka City University, Osaka, Osaka 558-8585, Japan

(Received 9 September 2002 / Accepted 29 October 2002 )

Abstract
We report the TeV gamma-ray observations of the nearby normal spiral galaxy NGC 253. At a distance of ~2.5 Mpc, NGC 253 is one of the nearest starburst galaxies. This relative closeness, coupled with the high star formation rate in the galaxy, make it a good candidate TeV gamma-ray source. Observations were carried out in 2000 and 2001 with the CANGAROO-II 10 m imaging atmospheric Cerenkov telescope. TeV gamma-ray emission is detected at the ~  level with a flux of at energies  >0.5 TeV. The data indicate that the emission region is broader than the point spread function of our telescope.

Key words: gamma rays: observation -- galaxies: individual: NGC 253 -- galaxies: starburst -- cosmic rays

Offprint request: R. Enomoto, enomoto@icrr.u-tokyo.ac.jp

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© ESO 2002

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