The X-ray properties of optically-selected clusters at z > 0.6

The ESO Distant Cluster Survey (EDisCS) comprises an extremely wellstudiedsample of opticallyselected cluster fields, including eightspectroscopicallyconfirmed clusters at z > 0.6 for which velocity dispersionsand weak lensing maps have already been derived. We have studied three fieldswith XMM to date and here propose a completion of the sample. The proposedobservations will allow us to: i) significantly expand the highredshift L_X sigma and T sigma relations; ii)study the Xray properties of the progenitorsof typical presentday clusters; iii) examine the inherent biases inXrayselected highredshift cluster surveys; and iv) test the validity ofvarious mass estimation methods at high redshift. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]