The Spatial Distribution of Metals in the Intergalactic Medium

Abstract

We investigate the impact of environment on the metallicity of the diffuse intergalactic medium. We use pixel correlation techniques to search for weak C IV and O VI absorption in the spectrum of quasar Q1422+231 in regions of the spectrum close to and far from galaxies at z~3. This is achieved both by using the positions of observed Lyman-break galaxies and by using strong C IV absorption as a proxy for the presence of galaxies near the line of sight. We find that the metal line absorption is a strong function of not only the H I optical depth, and thus gas density, but also proximity to highly enriched regions, and so proximity to galaxies. The parameter ``proximity to galaxies'' can account for some, but not all, of the scatter in the strength of C IV absorption for fixed H I. Finally, we find that even if we limit our analysis to the two-thirds of the pixels that are at least 600 km s-1 from any C IV line that is strong enough to detect unambiguously (τCIV>0.1), our statistical analysis reveals only slightly less C IV for fixed H I than when we analyze the whole spectrum. We conclude that while the metallicity is enhanced in regions close to (Lyman-break) galaxies, the enrichment is likely to be much more widespread than their immediate surroundings.