{
  "id": "astro-ph/0111134",
  "version": "v2",
  "published": "2001-11-07T01:48:12.000Z",
  "updated": "2002-01-14T00:23:19.000Z",
  "title": "The X-ray Spectra of Black Hole X-ray Novae in Quiescence as Measured by Chandra",
  "authors": [
    "A. K. H. Kong",
    "J. E. McClintock",
    "M. R. Garcia",
    "S. S. Murray",
    "D. Barret"
  ],
  "comment": "9 pages, 6 figures, accepted for publication in ApJ",
  "doi": "10.1086/339501",
  "categories": [
    "astro-ph"
  ],
  "abstract": "We present Chandra observations of black hole X-ray novae V404 Cyg, A0620-00, GRO J1655-40 and XTE J1550-564 in quiescence. Their quiescent spectra can be well fitted by a power-law model with slope $\\alpha \\sim 2$. While a coronal (Raymond-Smith) model is also a statistically acceptable representation of the spectra, the best fit temperatures of these models is $\\sim 5$ times higher than that seen in active stellar coronae. These four spectra of quiescent X-ray novae are all consistent with that expected for accretion via an advection-dominated accretion flow (ADAF) and inconsistent with that expected from a stellar corona. This evidence for continued accretion in quiescence further strengthens the case for the existence of event horizons in black holes. Both A0620-00 and GRO J1655-40 were fainter than in previous observations, while V404 Cyg was more luminous and varied by a factor of 2 in a few ksec. A reanalysis of the X-ray data for XTE J1550-564 shows that (like V404 Cyg and A0620-00) its luminosity exceeds the maximum prediction of the coronal model by a large factor. The 0.3-7 keV luminosity of the four sources studied ranges from $\\sim 10^{30}-10^{33}$ erg/s.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2002-01-14T00:23:19.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray spectra",
      "quiescence",
      "hole x-ray novae v404 cyg",
      "black hole x-ray novae v404"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}