Ultraviolet Line Emission From Metals in the Low-redshift Intergalactic Medium

Abstract

We use a high-resolution cosmological simulation that includes hydrodynamics, multiphase star formation, and galactic winds to predict the distribution of metal line emission at z similar to 0 from the intergalactic medium (IGM). We focus on two ultraviolet doublet transitions, O vi lambdalambda1032, 1038 and C IV lambdalambda1548, 1551. Emission from filaments with moderate overdensities is orders of magnitude smaller than the background, but isolated emission from enriched dense regions with T similar to 10(5)-10(5.5) K and characteristic size similar to50-100 kpc can be detected above the background. We show that the emission from these regions is substantially greater when we use the metallicities predicted by the simulation ( which includes enrichment through galactic winds) than when we assume a uniform IGM metallicity. Luminous regions correspond to volumes that have recently been influenced by galactic winds. We also show that the line emission is clustered on scales similar to1 h(-1) Mpc. We argue that although these transitions are not effective tracers of the warm-hot intergalactic medium, they do provide a route to study the chemical enrichment of the IGM and the physics of galactic winds.