Searching for Sharp Surface Brightness Discontinuities: a Systematic   Study of Cold Fronts in Galaxy Clusters
  We perform a systematic search of cold fronts in a sample of 62 clusters observed with XMM-Newton with redshift ranging from 0.01 to 0.3. We detect one or more cold fronts in 21 (34%) of our objects. A large fraction (87.5%) of nearby clusters 0.01 < z < 0.04 host a cold front while only 20% of the distant clusters, mostly merging clusters, do so. The absence of sharp surface brightness discontinuites in distant cool cores is most likely a consequence of the insufficent spatial resolution of our images. Some nearby cool core clusters show a dislocation between the surface brightness and the pressure peak. This implies that the cool central gas is displaced from the bottom of the gravitational potential well and likely sloshing. 
S. Ghizzardi, S. Molendi, A. Leccardi, M. Rossetti (IASF-Milano/INAF;   Italy)