JOINT X-RAYAND OPTICAL MEASUREMENTS OF THE MASS DISTRIBUTION OF THE DISTANT GALAXY CLUSTER Cl J0152.71357

We present joint X-ray and optical observations of the high-redshift (z ’ 0.83) lensing cluster Cl J0152.71357 made with the Chandra X-Ray Observatory and the Keck telescope. We confirm the existence of significant substructure at both X-ray and optical wavelengths in the form of two distinct clumps, whose temperatures are 6:6þ2:41:5 and 5:7 þ2:9 1:6 keV, respectively. The X-ray surface brightness profiles of the two clumps can be fitted by either a single -model or an NFW-like profile, the latter giving better fits to the central regions. We find that the X-ray–derived mass of this cluster is in good agreement with independent lensing measure-ments. While its appearance indicates that the cluster has not reached a dynamical equilibrium state, its X-ray luminosity LX, temperature T, and dynamical mass M are consistent with the well-defined LX-T and M-T relations for low-redshift galaxy clusters, which suggests that the dynamical properties of the clusters have remained almost unchanged since z 0.8