Volume 419, Number 3, June I 2004
|Page(s)||811 - 819|
|Section||Cosmology (including clusters of galaxies)|
|Published online||07 May 2004|
Metals in the intergalactic medium *
Institut d'Astrophysique de Paris – CNRS, 98bis Boulevard Arago, 75014 Paris, France
2 LERMA, Observatoire de Paris-Meudon, 61 avenue de l'Observatoire, 75014 Paris, France e-mail: email@example.com
3 Observatoire de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France
Corresponding author: B. Aracil, firstname.lastname@example.org
Accepted: 15 February 2004
We use high spectral resolution () and high signal-to-noise ratio ( per pixel) spectra of 19 high-redshift () quasars to investigate the metal content of the low-density intergalactic medium using pixel-by-pixel procedures. This high quality homogeneous survey gives the possibility to statistically search for metals at H i optical depths smaller than unity. We find that the gas is enriched in carbon and oxygen for neutral hydrogen optical depths > 1. Our observations strongly suggest that the C iv/H i ratio decreases with decreasing with . We do not detect C iv absorption statistically associated with gas of < 1. However, we observe that a small fraction of the low density gas is associated with strong metal lines as a probable consequence of the IGM enrichment being highly inhomogeneous. We detect the presence of O vi down to ~ 0.2 with log / ~ -2.0. We show that O vi absorption in the lowest density gas is located within ~300 km s-1 of strong H i lines. This suggests that this O vi phase may be part of winds flowing away from overdense regions. This effect is more important at the largest redshifts (z > 2.4). Therefore, at the limit of present surveys, the presence of metals in the underdense regions of the IGM is still to be demonstrated.
Key words: cosmology: observations / galaxies: halos / galaxies: ISM / quasars: absorption lines
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.