Chandra observations of RX J1347.5-1145:: the distribution of mass in the most X-ray-luminous galaxy cluster known

We present Chandra observations of RX J1347.5-1145, the most X-ray-luminous cluster of galaxies known. We report the discovery of a region of relatively hot, bright X-ray emission, located approximately 20 arcsec to the south-east of the main X-ray peak at a position consistent with the region of enhanced Sunyaev-Zel'dovich effect reported recently by Komatsu et al. We suggest that this region contains shocked gas resulting from a recent subcluster merger event. Excluding the data for the south-east quadrant, the cluster appears relatively relaxed. The X-ray gas temperature rises from kT similar to 6 keV within the central 25 h (50) (-1) kpc radius to a mean value of similar to16 keV between 0.1 and 0.5 h (50) (-1) Mpc. The mass profile for the relaxed regions of the cluster, determined under the assumption of hydrostatic equilibrium, can be parametrized by a Navarro, Frenk and White model with a scale radius r (s) similar to 0.4 h (50) (-1) Mpc and a concentration parameter csimilar to 6. The best-fitting Chandra mass model is in good agreement with independent measurements from weak gravitational lensing studies. Strong lensing data for the central regions of the cluster can also be explained by the introduction of an additional mass clump centred on the second brightest galaxy. We argue that this galaxy is likely to have been the dominant galaxy of the recently merged subcluster.