Shock Waves in Clusters of Galaxies: Nature and Properties

Abstract

During the formation of the large-scale structure of the Universe, the intracluster medium (ICM), which fills the volume of galaxy clusters and is composed of hot, high-beta plasma in the state of turbulence, is continuously disturbed by major and minor mergers of clumps as well as infall of the warm-hot intergalactic medium (WHIM) along filaments. Such dynamical activities induce shock waves, which are observed in radio and X-ray mostly in cluster outskirts. These shocks are collisionless, as in other astrophysical environments, and are thought to heat the plasma as well as accelerate cosmic rays (CRs) via diffusive shock acceleration (DSA) mechanism. Here, we present the properties of shocks in the ICM, studied with high-resolution simulations. We also discuss the implications our study on observations of radio relics and X-ray shocks.