The Slow Growth of Massive Galaxies in Rapidly Growing Dark Matter Halos

TL;DR

This paper investigates the apparent discrepancy between the rapid growth of dark matter halos and the slow stellar mass growth of massive galaxies at redshift less than 1, revealing that satellite galaxies dominate stellar mass in massive halos.

Contribution

It demonstrates that in massive dark matter halos, stellar mass growth of central galaxies is limited, with most stellar mass residing in satellite galaxies, explaining slow galaxy growth despite halo accretion.

Findings

Massive dark matter halos grow rapidly at z<1.

Stellar mass of central galaxies scales as halo mass to the one-third power.

Most stellar mass in massive halos is in satellite galaxies.

Abstract

In cold dark matter cosmologies, the most massive dark matter halos are predicted to undergo rapid growth at z<1. While there is the expectation that massive galaxies will also rapidly grow via merging, recent observational studies conclude that the stellar masses of the most massive galaxies grow by just 30 percent at z<1. We have used the observed space density and clustering of z<1 red galaxies in Bootes to determine how these galaxies populate dark matter halos. In the most massive dark matter halos, central galaxy stellar mass is proportional to halo mass to the power of a third and much of the stellar mass resides within satellite galaxies. As a consequence, the most massive galaxies grow slowly even though they reside within rapidly growing dark matter halos.