Evolution of Magnetic Fields in Galaxy Clusters

Abstract

Cosmological simulations of magnetic fields in galaxy clusters show that remarkable agreement between simulations and observations of Faraday rotation can be achieved assuming that seed fields of ≈ 10−9G where present at redshifts ≈ 15–20. Previous simulations showed that the structure of the seed field is irrelevant for the final intracluster field. On average, the field grows exponentially with decreasing cluster redshift, but merger events cause steep transient increases in the field strength. A set of new, high resolution simulations of clusters will allow us to study the predicted magnetic field in galaxy clusters in even more detail. Using the observed correlation between X-ray surface brightness and Faraday rotation measure we confirm that the magnetic field scales with the intracluster gas density. The observations of low temperature clusters also indicate that the central magnetic field strength is correlated with the cluster temperature, as predicted by the simulations.