We report on an XMM-Newton observation of RX J1347.5 - 1145 ( z=0.451 ) , the most luminous X-ray cluster of galaxies currently known , with a luminosity L _ { X } = 6.0 \pm 0.1 \times 10 ^ { 45 } erg/s in the [ 2-10 ] keV energy band .
We present the first temperature map of this cluster , which shows a complex structure .
It identifies the cool core and a hot region at radii 50-200 kpc to south-east of the main X-ray peak , at a position consistent with the subclump seen in the X-ray image .
This structure is probably an indication of a submerger event .
Excluding the data of the south-east quadrant , the cluster appears relatively relaxed and we estimate a total mass within 1.7 Mpc of 2.0 \pm 0.4 \times 10 ^ { 15 } M _ { \sun } .
We find that the overall temperature of the cluster is kT = 10.0 \pm 0.3 keV .
The temperature profile shows a decline in the outer regions and a drop in the centre , indicating the presence of a cooling core which can be modelled by a cooling flow model with a minimum temperature \sim 2 keV and a very high mass accretion rate , \dot { M } \sim 1900 \mbox { M } _ { \sun } / \mbox { yr } .
We compare our results with previous observations from ROSAT , ASCA and Chandra .