Clusters and Superclusters of Galaxies

Abstract

Rich clusters of galaxies are the most massive virialized systems known. Even though they contain only a small fraction of all galaxies, rich clusters provide a powerful tool for the study of galaxy formation, dark matter, large-scale structure, and cosmology.Superclusters, the largest known systems of galaxies, extend to ∼ 100hMpc in size and highlight the large-scale structure of the universe. This largescale structure reflects initial conditions in the early universe and places strong contraints on models of galaxy formation and on cosmology. Some of the questions that can be addressed with clusters and superclusters of galaxies include: How did galaxies and larger structures form and evolve? What is the amount, composition, and distribution of matter in clusters and larger structures? How does the cluster mass density relate to the matter density in the universe? What constraints can the cluster and supercluster data place on cosmology?I will discuss in these lectures some of the properties of clusters and superclusters of galaxies that can be used to investigate these topics.

The Hercules cluster in X-rays with XMM-Newton and Chandra

“…Galaxy clusters are generally thought of as relaxed and evolved systems with total masses of ∼10 14 − 10 15 M (McNamara & Nulsen 2007;Kravtsov & Borgani 2012) and large sizes of several Mpc. Observations of clusters, however, reveal that they contain a significant degree of substructure, indicating that they are dynamically evolving systems (Fabian 1992;Oegerle & Hill 2001). The substructures can be seen in the galaxy surface number density distribution (Geller & Beers 1982;Flin & Krywult 2006) and X-ray surface brightness (SB) maps of clusters (Gómez et al 1997;Jones & Forman 1999;Schuecker et al 2001) in the form of multiple peaks.…”

The complex intracluster medium of Abell 1569 and its interaction with central radio galaxies

“…Optical and X-ray observations of galaxy clusters reveal that they are dynamically evolving systems containing a significant degree of substructure (Fabian 1992;Oegerle & Hill 2001). The galaxy number density maps in the optical (Geller & Beers 1982;Flin & Krywult 2006) and X-ray surface brightness (SB) images (Gómez et al 1997b;Jones & Forman 1999;Schuecker et al 2001) of clusters often show multiple peaks corresponding to individual groups of galaxies.…”