{
  "id": "1002.3506",
  "version": "v1",
  "published": "2010-02-18T12:53:45.000Z",
  "updated": "2010-02-18T12:53:45.000Z",
  "title": "Early X-ray and optical observations of the soft gamma-ray repeater SGR 0418+5729",
  "authors": [
    "P. Esposito",
    "G. L. Israel",
    "R. Turolla",
    "A. Tiengo",
    "D. Götz",
    "A. De Luca",
    "R. P. Mignani",
    "S. Zane",
    "N. Rea",
    "V. Testa",
    "P. A. Caraveo",
    "S. Chaty",
    "F. Mattana",
    "S. Mereghetti",
    "A. Pellizzoni",
    "P. Romano"
  ],
  "comment": "The paper (10 pages) contains 6 colour figures and 2 tables; accepted for publication in MNRAS",
  "journal": "Monthly Notices of the Royal Astronomical Society, Vol. 405, pp. 1787-1795 (2010)",
  "doi": "10.1111/j.1365-2966.2010.16551.x",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Emission of two short hard X-ray bursts on 2009 June 5 disclosed the existence of a new soft gamma-ray repeater, now catalogued as SGR 0418+5729. After a few days, X-ray pulsations at a period of 9.1 s were discovered in its persistent emission. SGR 0418+5729 was monitored almost since its discovery with the Rossi X-ray Timing Explorer (2-10 keV energy range) and observed many times with Swift (0.2-10 keV). The source persistent X-ray emission faded by a factor 10 in about 160 days, with a steepening in the decay about 19 days after the activation. The X-ray spectrum is well described by a simple absorbed blackbody, with a temperature decreasing in time. A phase-coherent timing solution over the 160 day time span yielded no evidence for any significant evolution of the spin period, implying a 3-sigma upper limit of 1.1E-13 s/s on the period derivative and of 3E+13 G on the surface dipole magnetic field. Phase-resolved spectroscopy provided evidence for a significant variation of the spectrum as a function of the stellar rotation, pointing to the presence of two emitting caps, one of which became hotter during the outburst. Finally, a deep observation of the field of SGR 0418+5729 with the new Gran Telescopio Canarias 10.4-m telescope allowed us to set an upper limit on the source optical flux of i'>25.1 mag, corresponding to an X-ray-to-optical flux ratio exceeding 10000, consistent with the characteristics of other magnetars.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-02-18T12:53:45.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "soft gamma-ray repeater sgr",
      "optical observations",
      "early x-ray",
      "persistent x-ray emission",
      "short hard x-ray bursts"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "Wiley-Blackwell",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2010,
      "month": "Jul",
      "volume": 405,
      "number": 3,
      "pages": 1787
    },
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 846076,
      "adsabs": "2010MNRAS.405.1787E"
    }
  }
}