Investigating the Central Regions of the HIFLUGCS Clusters with Chandra

We present a preliminary analysis of the Chandra follow up to the HIFLUGCS sample (Hudson et al, in prep). By plotting the central temperature profiles, normalized to the global cluster temperature, against the fraction of the virial radius, we find no evidence for a universal central temperature profile. Similarly by fitting the central temperature profile to a powerlaw, we find a continuous range of values for the slope. Interpreting a positive temperature gradient as an indication of a cooling core, we find that exactly half (32 of 64) of the clusters in the HIFLUGCS sample are classified as cooling core clusters. Additionally, we find a flattening of the central entropy, consistent with other observations and predictions from simulations [3]. Perhaps the most interesting feature is the bi-modal distribution in the plot of global temperature versus central entropy. The distributions can be easily divided at 40 keV cm2. Interpreting the clusters with a low central entropy as cooling core clusters, 27 of the clusters are classified as cooling core clusters with this method.