  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 cents to the heating of the ICM. Shocks that are excited by the jets
contribute even less.
