XMM-newton observes Cl J0152.7-1357: a massive galaxy cluster forming at merger crossroads at z = 0.83

We present an analysis of a 50 ks XMM-Newton observation of the merging galaxy cluster Cl J0152.7-1357 at z = 0.83. In addition to the two main subclusters and an infalling group detected in an earlier Chandra observation of the system, XMM-Newton detects another group of galaxies possibly associated with the cluster. This group may be connected to the northern subcluster by a filament of cool (1.4_-0.1 ^+0.3 keV) X-ray-emitting gas and lies outside the estimated virial radius of the northern subcluster. The X-ray morphology agrees well with the projected galaxy distribution in new K-band imaging data presented herein. We use detailed spectral and imaging analysis of the X-ray data to probe the dynamics of the system and find evidence that another subcluster or group has recently passed through the northern subcluster. Cl J0152.7-1357 is an extremely dynamically active system, with mergers at different stages occurring along two perpendicular merger axes.