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Metals in the Intergalactic Medium

Bastien Aracil·Patrick Petitjean·Christophe Pichon·Jacqueline Bergeron
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Abstract

We use high spectral resolution (R=45000) and high signal-to-noise ratio (S/N \~ 35-70 per pixel) spectra of 19 high-redshift (2.1 1. Our observations strongly suggest that the CIV/HI ratio decreases with decreasing tau(HI) with log[tau(CIV)]=1.3xlog[tau(HI)]-3.2. We do not detect CIV absorption statistically associated with gas of tau(HI)<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 OVI down to tau(HI)~0.2 with log[tau(OVI)/tau(HI)] -2.0. We show that OVI absorption in the lowest density gas is located within ~300 km/s from strong HI lines. This suggests that this OVI 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.

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Bastien Aracil, Patrick Petitjean, Christophe Pichon, Jacqueline Bergeron. 2004-01-27. Metals in the Intergalactic Medium. https://doi.org/10.1051/0004-6361%3A20034346

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