Observation of an Extended Very High Energy Gamma-Ray Emission from MSH 15-52 with CANGAROO-III
Katagiri, H.; Edwards, P. G.; Gunji, S.; Mori, M.; Kubo, H.; Kushida, J.; Nishijima, K.; Nakamori, T.; Stamatescu, V.; Watanabe, S.; Hattori, T.; Inoue, K.; Yoshida, T.; Matsubara, Y.; Muraki, Y.; Suzuki, T.; Hara, T.; Kajino, F.; Bicknell, G. V.; Yamada, Y.; Mizumoto, Y.; Tanimori, T.; Enomoto, R.; Clay, R. W.; Hara, S.; Hayashi, S.; Higashi, Y.; Hirai, Y.; Kabuki, S.; Kawachi, A.; Kifune, T.; Kiuchi, R.; Mizukami, T.; Mizuniwa, R.; Muraishi, H.; Naito, T.; Nakano, S.; Nishida, D.; Ohishi, M.; Sakamoto, Y.; Seki, A.; Swaby, D. L.; Thornton, G.; Tokanai, F.; Tsuchiya, K.; Yamazaki, E.; Yanagita, S.; Yoshikoshi, T.; Yukawa, Y.
Japan, Australia
Abstract
We have observed the supernova remnant MSH 15-52 (G320.4-1.2), which contains the gamma-ray pulsar PSR B1509-58, using the CANGAROO-III imaging atmospheric Cerenkov telescope array from 2006 April to June. We detected gamma rays above 810 GeV at the 7 σ level during a total effective exposure of 48.4 hr. We obtained a differential gamma-ray flux at 2.35 TeV of (7.9 +/- 1.5stat+/- 1.7sys) × 10-13 cm-2 s-1 TeV-1, with a photon index of 2.21 +/- 0.39stat+/- 0.40sys, which is compatible with that of the H.E.S.S. observation in 2004. The morphology shows extended emission compared to our point spread function. We consider the plausible origin of the high-energy emission based on a multiwavelength spectral analysis and energetics arguments.