Stirring up the intracluster medium with substructures

Abstract:

The origin of the turbulent motion of the intracluster medium (ICM) has been a longstanding open question. Stirring by substructures (member galaxies and dark matter subhaloes) orbiting within a galaxy cluster is a possible mechanism to generate and maintain the ICM turbulence. We develop a semi-analytic model considering three processes of energy transfer from substructures to the ICM (dynamical friction, ram pressure, and sloshing), and propagation and dissipation of the deposited energy. The model reproduces the gas velocity structure derived from hydrodynamical simulations. We find that dynamical friction is responsible for explaining the strong turbulence (~ 500 km/s) in the cluster outskirts (> 1 Mpc), while sloshing explains the mild turbulence (~100 km/s) in the cluster centre. In the talk, we will also discuss implications for X-ray observations of the new generation, such as XRISM and eROSITA.