Volume 396, Number 2, December III 2002
|Page(s)||L11 - L15|
|Published online||03 December 2002|
Letter to the Editor
The warm-hot intergalactic medium at : Metal enrichment and ionization source*
Institut d'Astrophysique de Paris - CNRS, 98bis Boulevard Arago, 75014 Paris, France
2 LERMA, Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France
3 Observatoire Astronomique de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France
Corresponding author: J. Bergeron, firstname.lastname@example.org
Accepted: 31 October 2002
Results are presented for our search for warm-hot gas towards the quasar Q 0329-385. We identify ten O vi systems of which two are within 5000 km s-1 of zem and a third one should be of intrinsic origin. The seven remaining systems have H i column densities cm-2. At least ~1/3 of the individual O vi sub-systems have temperatures K and cannot originate in collisionally ionized gas. Photoionization by a hard UV background field reproduces well the ionic ratios for metallicities in the range solar, with possibly sub-solar N/C relative abundance. For , the sizes inferred for the O vi clouds are in some cases larger than the maximum extent implied by the Hubble flow. This constraint is fulfilled assuming a moderate overabundance of oxygen relative to carbon. For a soft UV ionizing spectrum, an overabundance of O/C is required, . For a hard(soft) U spectrum and , the O vi regions have overdensities .
Key words: cosmology: observations / intergalactic medium / galaxies: halos / quasars: absorption lines
© ESO, 2002
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