{
  "id": "1105.3586",
  "version": "v1",
  "published": "2011-05-18T10:33:26.000Z",
  "updated": "2011-05-18T10:33:26.000Z",
  "title": "X-Ray and Near-Infrared Observations of GX 339-4 in the Low/Hard State with Suzaku and IRSF",
  "authors": [
    "Megumi Shidatsu",
    "Yoshihiro Ueda",
    "Fumie Tazaki",
    "Tatsuhito Yoshikawa",
    "Takahiro Nagayama",
    "Tetsuya Nagata",
    "Nagisa Oi",
    "Kazutaka Yamaoka",
    "Hiromitsu Takahashi",
    "Aya Kubota",
    "Jean Cottam",
    "Ronald Remillard",
    "Hitoshi Negoro"
  ],
  "comment": "17pages, 15 figures, accepted for publication in PASJ (Suzaku and MAXI Special Issue)",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "X-ray and near-infrared ($J$-$H$-$K_{\\rm s}$) observations of the Galactic black hole binary GX 339--4 in the low/hard state were performed with Suzaku and IRSF in 2009 March. The spectrum in the 0.5--300 keV band is dominated by thermal Comptonization of multicolor disk photons, with a small contribution from a direct disk component, indicating that the inner disk is almost fully covered by hot corona with an electron temperature of $\\approx$175 keV. The Comptonizing corona has at least two optical depths, $\\tau \\approx 1,0.4$. Analysis of the iron-K line profile yields an inner disk radius of $(13.3^{+6.4}_{-6.0}) R_{\\rm g}$ ($R_{\\rm g} $ represents the gravitational radius $GM/c^2$), with the best-fit inclination angle of $\\approx50^\\circ$. This radius is consistent with that estimated from the continuum fit by assuming the conservation of photon numbers in Comptonization. Our results suggest that the standard disk of GX 339--4 is likely truncated before reaching the innermost stable circular orbit (for a non rotating black hole) in the low/hard state at $\\sim$1% of the Eddington luminosity. The one-day averaged near-infrared light curves are found to be correlated with hard X-ray flux with $F_{\\rm Ks} \\propto F_{\\rm X}^{0.45}$. The flatter near infrared $\\nu F_{\\nu}$ spectrum than the radio one suggests that the optically thin synchrotron radiation from the compact jets dominates the near-infrared flux. Based on a simple analysis, we estimate the magnetic field and size of the jet base to be $5\\times10^4$ G and $6\\times 10^8$ cm, respectively. The synchrotron self Compton component is estimated to be approximately 0.4% of the total X-ray flux.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2011-05-18T10:33:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "low/hard state",
      "near-infrared observations",
      "averaged near-infrared light curves",
      "galactic black hole binary gx",
      "x-ray flux"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1093/pasj/63.sp3.S785",
      "journal": "Publications of the Astronomical Society of Japan",
      "year": 2011,
      "month": "Nov",
      "volume": 63
    },
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 900528,
      "adsabs": "2011PASJ...63S.785S"
    }
  }
}