Hitomi observations of Perseus support heating by mixing

Abstract We compare the velocity dispersion of the intracluster medium (ICM) of the Perseus cluster of galaxies as observed by the Hitomi X-ray telescope to our three-dimensional hydrodynamical simulations of jet-inflated bubbles in cluster cooling flows and conclude that the observations support the mixing-heating mechanism of the ICM. In the mixing-heating mechanism, the ICM is heated by mixing of hot bubble gas with the ICM. This mixing is caused by vortices that are formed during the inflation process of the bubble. Sound waves and turbulence are also excited by the vortices, but they contribute less than 20 per cent to the heating of the ICM. Shocks that are excited by the jets contribute even less.