{
  "id": "astro-ph/0005045",
  "version": "v1",
  "published": "2000-05-02T19:34:33.000Z",
  "updated": "2000-05-02T19:34:33.000Z",
  "title": "FUSE Observations of O VI Absorption in the Galactic Halo",
  "authors": [
    "B. D. Savage",
    "K. R. Sembach",
    "E. B. Jenkins",
    "J. M. Shull",
    "D. G. York",
    "G. Sonneborn",
    "H. W. Moos",
    "S. D. Friedman",
    "J. C. Green",
    "W. R. Oegerle",
    "W. P. Blair",
    "J. W. Kruk",
    "E. M. Murphy"
  ],
  "comment": "8 pages, AASTeX preprint format. This paper will appear in a special issue of Astrophysical Journal Letters devoted to the first scientific results from the FUSE mission",
  "categories": [
    "astro-ph"
  ],
  "abstract": "Far-ultraviolet spectra of 11 AGNs observed by FUSE are analyzed to obtain measures of O VI 1031.93 A absorption occurring over very long paths through Milky Way halo gas. Strong O VI absorption is detected along 10 of 11 sight lines. Values of log [N(O VI) sin|b|] range from 13.80 to 14.64 with a median value of 14.21. The observations reveal the existence of a widespread but irregular distribution of O VI in the Milky Way halo. Combined with estimates of the O VI mid-plane density, n0 = 2x10^(-8) cm^(-3), from the Copernicus satellite, the FUSE observations imply an O VI exponential scale height of 2.7+/-0.4 kpc. We find that N(C IV)/N(O VI) ranges from 0.15 in the disk to 0.6 along four extragalactic sight lines. The changing ionization state of the gas from the disk to the halo is consistent with a systematic decrease in the scale heights of Si IV, C IV, N V, to O VI from ~5.1 to ~2.7 kpc. While conductive heating models can account for the highly ionized atoms at low |z|, a combination of models (and processes) appears to be required to explain the highly ionized atoms found in the halo. The greater scale heights of Si IV and C IV compared to O VI suggest that some of the Si IV and C IV in the halo is produced in turbulent mixing layers or by photoionization by hot halo stars or the extragalactic background.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2000-05-02T19:34:33.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "vi absorption",
      "fuse observations",
      "galactic halo",
      "milky way halo gas",
      "vi exponential scale height"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 545636,
      "adsabs": "2000astro.ph..5045S"
    }
  }
}