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 sub-halos 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 catalogue 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 intra-cluster stars, and the predicted amounts of the intra-cluster 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 Mh ∼ 10 hM⊙. If all these stars end up in the intra-cluster component (Max), or maximum of them are accreted into the central galaxy (Min), then we can predict that a maximum ∼ 19% and a minimum ∼ 5% of the total stars in the whole universe are in terms of the diffused intra-cluster component. In the former case, in massive halos with Mh ∼ 10 15 hM⊙, the stellar mass of the intra-cluster component is roughly 6 times as large as that of the central galaxy. This factor decreases to ∼ 2, 1 and 0.1 in halos with Mh ∼ 10 , 10, and 10 hM⊙, respectively. The total amount of stars stripped from satellite galaxies is insufficient to build up the central galaxies in halos with masses . 10hM⊙, and so the quenching of star formation must occur in halos with higher masses. In semi-analytical 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. Subject headings: dark matter large-scale structure of universe galaxies: halos