The Subhalo-Satellite Connection and the Fate of Disrupted Satellite Galaxies

In the standard paradigm, satellite galaxies are believed to be associated with the population of dark matter subhalos. The assumption usually made is that the relationship between satellite galaxies and subhalos is similar to that between central galaxies and host halos. In this paper, we use the conditional stellar mass functions of satellite galaxies obtained from a large galaxy group catalog together with models of the subhalo mass functions to explore the consequences of such assumption in connection to the stellar mass function of satellite galaxies and the fraction and fate of stripped stars from satellites in galaxy groups and clusters of different masses. The majority of the stripped stars in massive halos are predicted to end up as intracluster stars, and the predicted amounts of the intracluster component as a function of the velocity dispersion of galaxy system match well the observational results obtained by Gonzalez et al. (2007). The fraction of the mass in the stripped stars to that remain bound in the central and satellite galaxies is the highest (~40% of the total stellar mass) in halos with masses M_h ~ 10¹⁴ h ^-1 M _sun. If all these stars end up in the intracluster component (Max), or a maximum amount of these stars is accreted into the central galaxy (Min), then the maximum fraction of the total stars in the whole universe that is in the diffused intracluster component is ~19%, and the minimum is ~5%. In the case of "Max," the stellar mass of the intracluster component in massive halos with M_h ~ 10¹⁵ h ^-1 M _sun is roughly six times as large as that of the central galaxy. This factor decreases to ~2, 1, and 0.1 in halos with M_h ~ 10¹⁴, 10¹³, and 10¹² h ^-1 M _sun, respectively. The total amount of stars stripped from satellite galaxies is insufficient to build up the central galaxies in halos with masses lsim10^12.5 h ^-1 M _sun, and so the quenching of star formation must occur in halos with higher masses. In semianalytical models and simulations that do not resolve the diffused component, caution must be exercised when using the observed stellar mass/luminosity function of galaxies to constrain the star formation, feedback and merger processes in dark matter halos.