Turbulence Generation by Substructure Motion in Clusters of Galaxies

Abstract

Clusters of galaxies form through major merger and/or absorption of smaller groups. In fact, some characteristic structures such as cold fronts, which are likely relevant to moving substructures, are found by {\it Chandra}. It is expected that moving substructures generate turbulence in the intracluster medium (ICM). Such turbulence probably plays a crucial role in mixture and transport of gas energy and heavy elements, and particle acceleration. The {\it Astro-E2} satellite, which is planned to be launched in 2005, will detect broadened lines due to turbulent motion. In order to explore the above-mentioned issues, it is important to investigate the generation processes and structure of ICM turbulence. We investigate the ICM dynamical evolution in and around a moving substructure with three-dimensional hydrodynamical simulations. Eddy-like structures develop near the boundary between the substructure and the ambient ICM through Kelvin-Helmholtz instabilities. Because of these structures, characteristic patterns appear in the line-of-sight velocity distribution of the ICM.