Outstanding Issues in Merging Galaxy Clusters

Abstract

Clusters of galaxies form through successive mergers of clumps in the history of the universe. During the course, shocks and turbulence are induced in clusters, and magnetic fields and cosmic rays, in addition to hot plasma, are produced in the intracluster medium (ICM). A comprehensive picture of the formation and evolution of galaxy clusters and the astrophysical processes in the ICM has been established through radio and X-ray observations, as well as theoretical and simulation studies. Yet, there are a number of issues that remain to be further examined. In this talk, I will discuss several of them from a theorist’s point of view.