Clusters of galaxies

Abstract

This chapter focuses on galaxy clusters, tackling three aspects. Firstly, we look at clusters as laboratories, where we can study galaxy evolution and the interaction of galaxies with their environment. By measuring the properties of galaxies in clusters as a function of redshift, we can build a statistical history of galaxy formation and test this against theoretical models. Secondly, we look at the diffuse intra-cluster medium (ICM) that pervades galaxy clusters. This plasma makes accounts for the vast majority of baryons in the cluster. X-ray emission from the plasma can be used to measure the gravitational potential and to trace the thermal history of the universe. Finally, we look at clusters as probes of cosmology and their role in complementing the cosmic microwave background in constraining cosmological parameters.