{
  "id": "0909.5225",
  "version": "v1",
  "published": "2009-09-28T21:57:21.000Z",
  "updated": "2009-09-28T21:57:21.000Z",
  "title": "The First Detection of [O IV] from an Ultraluminous X-ray Source with Spitzer. II. Evidence for High Luminosity in Holmberg II ULX",
  "authors": [
    "C. T. Berghea",
    "R. P. Dudik",
    "K. A. Weaver",
    "T. R Kallman"
  ],
  "comment": "Accepted by ApJ",
  "categories": [
    "astro-ph.HE",
    "astro-ph.CO"
  ],
  "abstract": "This is the second of two papers examining Spitzer Infrared Spectrograph (IRS) observations of the ultraluminous X-ray source (ULX) in Holmberg II. Here we perform detailed photoionization modeling of the infrared lines. Our analysis suggests that the luminosity and morphology of the [O IV] 25.89 $\\mu$m emission line is consistent with photoionization by the soft X-ray and far ultraviolet (FUV) radiation from the accretion disk of the binary system and inconsistent with narrow beaming. We show that the emission nebula is matter-bounded both in the line of sight direction and to the east, and probably radiation-bounded to the west. A bolometric luminosity in excess of 10$^{40}$ erg s$^{-1}$ would be needed to produce the measured [O IV] flux. We use modeling and previously published studies to conclude that shocks likely contribute very little, if at all, to the high-ionization line fluxes observed in the Holmberg II ULX. Additionally, we find that the spectral type of the companion star has a surprisingly strong effect on the predicted strength of the [O IV] emission. This finding could explain the origin of [O IV] in some starburst systems containing black hole binaries.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-09-28T21:57:21.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "ultraluminous x-ray source",
      "first detection",
      "high luminosity",
      "examining spitzer infrared spectrograph",
      "systems containing black hole binaries"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/708/1/364",
      "journal": "The Astrophysical Journal",
      "year": 2010,
      "month": "Jan",
      "volume": 708,
      "number": 1,
      "pages": 364
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 832468,
      "adsabs": "2010ApJ...708..364B"
    }
  }
}