CONSTRAINING SATELLITE GALAXY STELLAR MASS LOSS AND PREDICTING INTRAHALO LIGHT. I. FRAMEWORK AND RESULTS AT LOW REDSHIFT

We introduce a new technique that uses galaxy clustering to constrain how satellite galaxies lose stellar mass and contribute to the diffuse intrahalo light (IHL). We implement two models that relate satellite galaxy stellar mass loss to the detailed knowledge of subhalo dark matter mass loss. Model 1 assumes that the fractional stellar mass loss of a galaxy, from the time of merging into a larger halo until the final redshift, is proportional to the fractional amount of dark matter mass loss of the subhalo it lives in. Model 2 accounts for a delay in the time that stellar mass is lost due to the fact that the galaxy resides deep in the potential well of the subhalo and the subhalo may experience dark matter mass loss for some time before the galaxy is affected. We use these models to predict the stellar masses of a population of galaxies and we use abundance matching to predict the clustering of several r-band luminosity threshold samples from the Sloan Digital Sky Survey. Abundance matching assuming no stellar mass loss (akin to abundance matching at the time of subhalo infall) overestimates the correlation function on small scales (less than or similar to 1 Mpc), while allowing too much stellar mass loss leads to an underestimate of small-scale clustering. For each luminosity threshold sample, we are thus able to constrain the amount of stellar mass loss required to match the observed clustering. We find that satellite galaxy stellar mass loss is strongly luminosity dependent, with less luminous satellite galaxies experiencing substantially more efficient stellar mass loss than luminous satellites. With constrained stellar mass loss models, we can infer the amount of stellar mass that is deposited into the IHL. We find that both of our model predictions for the mean amount of IHL as a function of halo mass are consistent with current observational measurements. However, our two models predict a different amount of scatter in the IHL from halo to halo, with Model 2 being favored by observations. This demonstrates that a comparison to IHL measurements provides independent verification of our stellar mass loss models, as well as additional constraining power.