Turbulence Generation by Substructure Motion in Clusters of Galaxies

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 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 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.