Enrichment of the intergalactic medium by radiation pressure-driven dust efflux

The presence of metals in hot cluster gas and in Ly absorbers, as well as t he mass-metallicity relation of observed galaxies, suggest that galaxies lo se a significant fraction of their metals to the intergalactic medium (IGM) . Theoretical studies of this process have concentrated on metal removal by dynamical processes or supernova-driven winds. Here we investigate the enr ichment of the IGM by the expulsion of dust grains from galaxies by radiati on pressure. We use already completed cosmological simulations to which we add dust, assuming that most dust can reach the equilibrium point between r adiation pressure and gravitational forces. We find that the expulsion of d ust and its subsequent (partial) destruction in the IGM can plausibly accou nt for the observed level of C and Si enrichment of the z = 3 IGM. At low z , dust ejection and destruction could explain a substantial fraction of the metals in clusters, but it cannot account for all of the chemical species observed. Dust expelled by radiation pressure could give clusters a visual opacity of up to 0.2-0.5 mag in their central regions, even after destructi on by the hot intracluster medium; this value is interestingly close to lim its and claimed observations of cluster extinction. We also comment on the implications of our results for the opacity of the general IGM. Finally, we suggest a possible "hybrid" scenario in which winds expel gas and dust int o galaxy halos but in which radiation pressure distributes the dust uniform ly through the IGM.