Cangaroo-III search for TeV gamma rays from two clusters of galaxies
Date
2009
Authors
Clay, R.
Stamatescu, V.
Swaby, D.
Thornton, G.
Kiuchi, R.
Mori, M.
Bicknell, G.
Edwards, P.
Enomoto, R.
Gunji, S.
Editors
Advisors
Journal Title
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Volume Title
Type:
Journal article
Citation
The Astrophysical Journal: an international review of astronomy and astronomical physics, 2009; 704(1):240-246
Statement of Responsibility
R. Kiuchi, M. Mori, G. V. Bicknell, R. W. Clay, P. G. Edwards, R. Enomoto, S. Gunji, S. Hara, T. Hara, T. Hattori, S. Hayashi, Y. Higashi, Y. Hirai, K. Inoue, C. Itoh, S. Kabuki, F. Kajino, H. Katagiri, A. Kawachi, T. Kifune, H. Kubo, J. Kushida, Y. Matsubara, T. Mizukami, Y. Mizumoto, R. Mizuniwa, H. Muraishi, Y. Muraki, T. Naito, T. Nakamori, S. Nakano, D. Nishida, K. Nishijima, M. Ohishi, Y. Sakamoto, A. Seki, V. Stamatescu, T. Suzuki, D. L. Swaby, T. Tanimori, G. Thornton, F. Tokanai, K. Tsuchiya, S. Watanabe, Y. Yamada, E. Yamazaki, S. Yanagita, T. Yoshida, T. Yoshikoshi and Y. Yukawa
Conference Name
Abstract
Because accretion and merger shocks in clusters of galaxies may accelerate particles to high energies, clusters are candidate sites for the origin of ultra-high-energy (UHE) cosmic rays. A prediction was presented for gamma-ray emission from a cluster of galaxies at a detectable level with the current generation of imaging atmospheric Cherenkov telescopes. The gamma-ray emission was produced via inverse Compton upscattering of cosmic microwave background photons by electron-positron pairs generated by collisions of UHE cosmic rays in the cluster. We observed two clusters of galaxies, Abell 3667 and Abell 4038, searching for very high energy gamma-ray emission with the CANGAROO-III atmospheric Cherenkov telescope system in 2006. The analysis showed no significant excess around these clusters, yielding upper limits on the gamma-ray emission. From a comparison of the upper limit for the northwest radio relic region of Abell 3667 with a model prediction, we derive a lower limit for the magnetic field of the region of ~0.1 μG. This shows the potential of gamma-ray observations in studies of the cluster environment. We also discuss the flux upper limit from cluster center regions using a model of gamma-ray emission from neutral pions produced in hadronic collisions of cosmic-ray protons with the intracluster medium. The derived upper limit of the cosmic-ray energy density within this framework is an order of magnitude higher than that of our Galaxy
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© IOP Publishing 2009. Submitted to Cornell University’s online archive www.arXiv.org in 2009 by Ryuta Kiuchi.Post-print sourced from www.arxiv.org.