{
  "id": "0908.3301",
  "version": "v1",
  "published": "2009-08-23T13:52:47.000Z",
  "updated": "2009-08-23T13:52:47.000Z",
  "title": "CANGAROO-III search for TeV Gamma-rays from two clusters of galaxies",
  "authors": [
    "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",
    "Y. Yukawa"
  ],
  "comment": "7 pages, 6 figures, Accepted in ApJ",
  "categories": [
    "astro-ph.HE"
  ],
  "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 (CMB) 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 north-west 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 micro G. 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 intra-cluster medium (ICM). The derived upper limit of the cosmic-ray energy density within this framework is an order of magnitude higher than that of our Galaxy.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-08-23T13:52:47.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gamma-ray emission",
      "tev gamma-rays",
      "cangaroo-iii search",
      "cangaroo-iii atmospheric cherenkov telescope system",
      "north-west radio relic region"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/704/1/240",
      "journal": "The Astrophysical Journal",
      "year": 2009,
      "month": "Oct",
      "volume": 704,
      "number": 1,
      "pages": 240
    },
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 829338,
      "adsabs": "2009ApJ...704..240K"
    }
  }
}