{
  "id": "1808.07880",
  "version": "v1",
  "published": "2018-08-23T18:00:07.000Z",
  "updated": "2018-08-23T18:00:07.000Z",
  "title": "The X-ray catalog of spectroscopically identified Galactic O stars: Investigating the dependence of X-ray luminosity on stellar and wind parameters",
  "authors": [
    "A. Nebot Gomez-Moran",
    "L. M. Oskinova"
  ],
  "comment": "18 pages, 16 figures, 5 tables",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "The X-ray emission of O-type stars was first discovered in the early days of the Einstein satellite. Since then many different surveys have confirmed that the ratio of X-ray to bolometric luminosity in O-type stars is roughly constant, but there is a paucity of studies that account for detailed information on spectral and wind properties of O-stars. Recently a significant sample of O stars within our Galaxy was spectroscopically identified and presented in the Galactic O-Star Spectroscopic Survey (GOSS). At the same time, a large high-fidelity catalog of X-ray sources detected by the XMM-Newton X-ray telescope was released. Here we present the X-ray catalog of O stars with known spectral types and investigate the dependence of their X-ray properties on spectral type as well as stellar and wind parameters. We find that, among the GOSS sample, 127 O-stars have a unique XMM-Newton source counterpart and a Gaia data release 2 (DR2) association. Terminal velocities are known for a subsample of 35 of these stars. We confirm that the X-ray luminosities of dwarf and giant O stars correlate with their bolometric luminosity. For the subsample of O stars with measure terminal velocities we find that the X-ray luminosities of dwarf and giant O stars also correlate with wind parameters. However, we find that these correlations break down for supergiant stars. Moreover, we show that supergiant stars are systematically harder in X-rays compared to giant and dwarf O-type stars. We find that the X-ray luminosity depends on spectral type, but seems to be independent of whether the stars are single or in a binary system. Finally, we show that the distribution of log(Lx/Lbol) in our sample stars is non-Gaussian, with the peak of the distribution at log(Lx/Lbol) around -6.6.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-08-23T18:00:07.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray luminosity",
      "wind parameters",
      "x-ray catalog",
      "spectroscopically identified galactic",
      "o-type stars"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}