Are we missing the X-ray under-luminous clusters

We propose to observe a Planck SZ selected, complete sample of 15 Xray underluminous galaxy clusters with XMMNewton. This largely unstudied population ofgalaxy clusters has important consequences for cosmology. Moreover, since theunderluminous clusters are expected to be undergoing major mergers, this sampleprovides a great opportunity to quantify energy redistribution among thermaland nonthermal particles, study heat transport and enrichment evo lution. Werequest 175ks of XMMNewton time to cover the 11 clusters which lackgoodquality observations. With these data, we will determine their dynamicalstate and history, examine the processes responsible for gas heating, andmeasure the impact of such powerful mergers on cosmological studies. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]