Resolving the central region of a very luminous galaxy cluster at z~ 0.7

We propose to image Xclass 2305, a bright galaxy cluster newly discovered in XMM archival data and located at zphot = 0.7. The derived temperature and luminosity correspond to a total cluster mass 5 x 10^14 M _sun assuming standard scaling relations. No hint of a S-Z decrement is seen in Planck data, which may indicate either contamination of XMM data by an X-ray point-source or a central luminosity excess due a cool core. Validation of either one or the other hypothesis will make this object particularly interesting as it belongs to the few known high-redshift, luminous X-ray clusters that will play a major role in the eROSITA era. The observation will exploit Chandra angular resolution to detect a point-source within the central cluster emission down to 10% contamination level.