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 is proportional to the fractional amount of dark matter mass loss of its subhalo. Model 2 accounts for a delay in the time that stellar mass is lost since the galaxy resides deep in the potential well of the subhalo which 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 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) over-estimates the correlation function on small scales (<~ 1 Mpc), while allowing too much stellar mass loss leads to an under-estimate. For each sample, we are thus able to constrain the amount of stellar mass loss required to match the observed clustering. We find that less luminous satellite galaxies experience more efficient stellar mass loss than luminous satellites. From these 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. (Abridged)