Turbulence and Magnetic Fields in the Outskirts of Clusters of Galaxies

Abstract

Magnetic fields in galaxy clusters, at least in their outskirts, are conjectured to be originated by small-scale dynamo due to turbulence in the intracluster medium (ICM). The so-called Sausage relic, one of giant radio relics in a cluster outskirt, on the other hand, posses magnetic fields of a few microG strength and a Mpc scale, so challenges the turbulence origin of cluster magnetic fields. The turbulence in the ICM is induced in highly stratified backgrounds due to the cluster gravity, and also it is driven sporadically by major mergers during the hierarchical formation of clusters. To get quantitative measures for turbulence and magnetic fields in such environments, we performed a series of simulations using a newly developed, high-accurate MHD code, and followed the development of turbulence and the amplification of magnetic fields. We here present early results, trying to answer whether turbulence dynamo could explain observed magnetic fields in cluster outskirts or other mechanisms need to be invoked.