{
  "id": "1002.2431",
  "version": "v1",
  "published": "2010-02-11T21:02:39.000Z",
  "updated": "2010-02-11T21:02:39.000Z",
  "title": "Fermi Discovery of Gamma-ray Emission from the Globular Cluster Terzan 5",
  "authors": [
    "A. K. H. Kong",
    "C. Y. Hui",
    "K. S. Cheng"
  ],
  "comment": "4 pages, 2 figures; accepted for publication in ApJL",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We report the discovery of gamma-ray emission from the Galactic globular cluster Terzan 5 using data taken with the Fermi Gamma-ray Space Telescope, from 2008 August 8 to 2010 January 1. Terzan 5 is clearly detected in the 0.5-20 GeV band by Fermi at ~27\\sigma level. This makes Terzan 5 as the second gamma-ray emitting globular cluster seen by Fermi after 47 Tuc. The energy spectrum of Terzan 5 is best represented by an exponential cutoff power-law model, with a photon index of ~1.9 and a cutoff energy at ~3.8 GeV. By comparing to 47 Tuc, we suggest that the observed gamma-ray emission is associated with millisecond pulsars, and is either from the magnetospheres or inverse Compton scattering between the relativistic electrons/positrons in the pulsar winds and the background soft photons from the Galactic plane. Furthermore, it is suggestive that the distance to Terzan 5 is less than 10 kpc and > 10 GeV photons can be seen in the future.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-02-11T21:02:39.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gamma-ray emission",
      "fermi discovery",
      "second gamma-ray emitting globular cluster",
      "exponential cutoff power-law model",
      "fermi gamma-ray space telescope"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/2041-8205/712/1/L36",
      "journal": "The Astrophysical Journal",
      "year": 2010,
      "month": "Mar",
      "volume": 712,
      "number": 1
    },
    "note": {
      "typesetting": "TeX",
      "pages": 4,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 845767,
      "adsabs": "2010ApJ...712L..36K"
    }
  }
}