Measurements of the Gas Temperature and Iron Abundance Distribution in the Coma Cluster

Abstract

The medium energy X-ray detectors onboard the EXOSAT Observatory have been used to determine the gas temperature at several positions in the Coma Cluster of galaxies. We find evidence at greater than 95% confidence for a higher temperature in the center of the cluster than in a position approximately 45' off-center. No difference in iron abundance is observed between the center and off-center regions and the equilibrium model for the distribution of elements in the Coma Cluster of Abramopoulos, Chanan, and Ku can be rejected with greater than 99.5% confidence, in favor of a model with more uniform composition. We offer a phenomenological model of the Coma Cluster, which is consistent with the data presented here, as well as the imaging data from the Einstein Observatory and the Tenma X-ray spectrum. The model has a central isothermal region of temperature ~9 keV extending to ~25' (~1 Mpc). Beyond this radius the temperature falls as a polytrope with index ~1.6.