Characterizing the Intracluster Medium Temperature Distribution in Galaxy Clusters

We measure for the first time the intracluster medium temperature distributions for 62 galaxy clusters in the HIFLUGCS, an X-ray flux-limited sample, with available X-ray data from XMM-Newton. We search for correlations between the width of the temperature distributions and other cluster properties, including median cluster temperature, luminosity, size, presence of a cool core, AGN activity, and dynamical state. We use a Markov Chain Monte Carlo analysis which models the ICM as a collection of X-ray emitting smoothed particles of plasma. Each smoothed particle is given its own set of parameters, including temperature, spatial position, redshift, size, and emission measure. This allows us to measure the width of the temperature distribution, median temperature, and total emission measure of each ccluster. Of all 62 clusters, none have a temperature width consistent with isothermality. Counterintuitively, we also find that the temperature distribution widths of disturbed clusters tend to be wider than in relaxed clusters. The presence of cluster to cluster variations in the shape of the temperature distributions and intrinsic scatter in kT of ~0.55 keV suggest the exact details of each cluster's unique thermal and dynamic history probably have a significant effect on the temperature distribution. This potentially makes kT a very useful quantity, both for determining the dynamical state of a cluster independently of its cooling status, and for investigating the interplay between ICM cooling and mergers.