Correlations between OVI absorbers and galaxies at low redshift

We investigate the relationship between galaxies and metal-line absorption systems in a large-scale cosmological simulation with galaxy formation. Our detailed treatment of metal enrichment and nonequilibrium calculation of oxygen species allow us, for the first time, to carry out quantitative calculations of the cross-correlations between galaxies and O VI absorbers. We find the following: ( 1) The cross-correlation strength depends weakly on the absorption strength but strongly on the luminosity of the galaxy. ( 2) The correlation distance increases mono-tonically with luminosity from similar to 0.5-1 h(-1) Mpc for 0.1L(*) galaxies to similar to 3-5 h(-1) Mpc for L-* galaxies. (3) The correlation distance has a complicated dependence on absorber strength, with a luminosity- dependent peak. ( 4) Only 15% of O vi absorbers lie near >= L-z* galaxies. The remaining 85%, then, must arise near lower luminosity galaxies; however, the positions of those galaxies is not well correlated with the absorbers. This may point to pollution of intergalactic gas predominantly by smaller galaxies. (5) There is a subtle trend that for >= 0.5L(z,*) galaxies, there is a positive correlation between absorber strength and galaxy luminosity in the sense that stronger absorbers have a slightly higher probability of finding such a large galaxy at a given projection distance. For less luminous galaxies, there seems to be a negative correlation between luminosity and absorber strength.