Shredded galaxies as the source of diffuse intrahalo light on varying scales

We make predictions for diffuse stellar mass fractions in dark matter halos from the scales of small spiral galaxies to those of large galaxy clusters. We use an extensively tested analytic model for subhalo infall and evolution and empirical constraints from galaxy survey data to set the stellar mass in each accreted subhalo, which is added to the diffuse light as subhalos become disrupted due to interactions within their hosts. We predict that the stellar mass fraction in diffuse, intrahalo light should rise on average from similar to 0.5% to similar to 20% from small galaxy halos (similar to 10(11) M-circle dot) to poor groups (similar to 10(13) M-circle dot). The trend with mass flattens considerably beyond the group scale, increasing weakly from a fraction of similar to 20% in poor galaxy clusters (similar to 10(14) M-circle dot) to roughly similar to 30% in massive clusters (similar to 10(15) M-circle dot). The mass-dependent diffuse light fraction is governed primarily by the empirical fact that the mass-to-light ratio in galaxy halos must vary as a function of halo mass. Galaxy halos have little diffuse light because they accrete most of their mass in small subhalos that themselves have high mass-to-light ratios; stellar halos around galaxies are built primarily from disrupted dwarf-irregular-type galaxies with M-* similar to 10(8.5) M-circle dot. The diffuse light in group and cluster halos is built from satellite galaxies that form stars efficiently; intracluster light is dominated by material liberated from massive galaxies with M-* similar to 10(11) M-circle dot. Our results are consistent with existing observations spanning the galaxy, group, and cluster scale; however, they can be tested more rigorously in future deep surveys.