XRISM observations of the cooling flow cluster A2029 support heating by mixing

Abstract

I argue that the mixing-heating mechanism of the intracluster medium (ICM) is compatible with the new observations by the X-ray telescope XRISM that show the dispersion velocity in the cooling flow cluster of galaxies A2029 to be 169 km/s. Past jets from the central supermassive black hole induced turbulence; the velocity dispersion value indicates that the jets were powerful, as expected in the mixing-heating mechanism. Although the kinetic energy of the ICM turbulence that XRISM finds is short of heating the ICM and counter radiative cooling, the turbulence is fast enough to mix the hot shocked jets' material with the ICM on time scales shorter than the radiative cooling time. The support of the mixing-heating mechanism from determining the turbulent velocity I claim for A2029 is similar to the conclusion from the X-ray observations by the X-ray telescope Hitomi of the Perseus cluster.