[Normal Galaxies, Clusters of Galaxies -- Oral ]

A detailed analysis of the cores of HIFLUGCS galaxy clusters: ICM cooling and AGN heating

Rupal Mittal, AIfA (Bonn) / RIT (Rochester)
Thomas Reiprich (AIfA), Paul Nulsen (CfA), Craig Sarazin (U. Virginia), Heinz Andernach (AIfA), Tracy Clarke (NRL), Daniel Hudson (AIfA)

The physics regulating the dense gas at the centers of galaxy clusters is far from being fully understood. Moreover, no comprehensive and systematic census of observed, detailed, properties of cluster cores exists up to now. We aim to put the statistical description of clustercenters on a firm new footing in order to: (1) gain insight into the physical processes governing cluster cores and (2) identify the best parameter for characterizing cool-core clusters and quantify its relation to other parameters. We summarize 16 widely used as well as new cool-core diagnostics and apply them to the largest complete and well-controlled cluster sample with available high quality data (HIghest X-ray FLUx Galaxy Cluster Sample, >4.5 Ms of cleaned Chandra data). We show that the cooling flow discrepancy is very unlikely due to the recent formation ofcooling flows, hence demonstrating the need for a heatingmechanism. Based on >140 radio flux-density measurements for the entire HIFLUGCS sample, we provide statistical and quantitative evidence supporting the AGN heating scenario. Lastly, we show that both ICM cooling as well as AGN heating are likely to influence the L-T relation but on different scales.