The hierarchical clustering method: abundance and properties of local satellite populations

Abstract

ABSTRACT The faint satellites of the local Universe provide an important benchmark for our understanding of structure formation and galaxy formation, but satellite populations are hard to identify beyond the Local Group. We recently developed an iterative method to quantify satellite abundance using galaxy clustering and tested it on a local sample in the COSMOS field, where accurate photometric redshifts are available for a large number of faint objects. In this paper, we consider the properties of these satellite populations in more detail, studying the satellite stellar mass function (SSMF), the satellite-central connection, and quenching as a function of satellite and central mass and colour. Despite the limited sample size, our results show good consistency with those from much larger surveys and constrain the SSMF down to some of the lowest primary masses considered to date. We reproduce several known trends in satellite abundance and quenching, and find evidence for one new one, a dependence of the quiescent fraction on the primary-to-secondary halo mass ratio. We discuss the prospects for the clustering method in current and forthcoming surveys.