  We present Chandra observations of RXJ1347.5-1145, 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 southeast of
the main X-ray peak, at a position consistent with the region of enhanced
Sunyaev-Zeldovich effect reported by Komatsu et al. (2001). We suggest that
this region contains shocked gas resulting from a recent subcluster merger
event. Excluding the data for the southeast quadrant, the cluster appears
relatively relaxed. The X-ray gas temperature rises from kT~6 keV within the
central 25 h_50^{-1} kpc radius to a mean value of ~16 keV between 0.1-0.5
h_50^{-1} Mpc. The mass profile for the relaxed regions of the cluster,
determined under the assumption of hydrostatic equilibrium, can be
parameterized by a Navarro, Frenk & White (1997) model with a scale radius
r_s~0.4 h_50^{-1} Mpc and a concentration parameter c~6. The best-fit 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 be also 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.
