Metal Enhancements in the X-ray Gas around Central Cluster Galaxies

Abstract

The X-ray emission by hot gas around the central galaxies of galaxy clusters is commonly modeled assuming the existence of steady-state, multiphase cooling flows. The inflowing gas will be chemically enriched by type Ia supernovae and stellar mass loss occurring in the outer parts of the central galaxy. This may give rise to a substantial metallicity enhancement towards the center, whose amplitude is proportional to the ratio of the central galaxy luminosity to the mass inflow rate. The metallicity of the hotter phases is expected to be higher than that of the colder, denser phases. The metallicity profile expected for the Centaurus cluster is in good agreement with the iron abundance gradient recently inferred from ASCA measurements (Fukazawa et al. 1994). However, current data do not rule out alternative models where cooling is balanced by some heat source. In either case, the enhancement expected from injection by type Ia supernovae is roughly as observed. Most of this work is described in more detail in Reisenegger, Miralda-Escudé, \& Waxman (1996; astro-ph/9511044).