A first XMM-Newton look at the most X-ray-luminous galaxy cluster RX J1347.5-1145

We present the first results from 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 LX = 6.0 ± 0.1 × 1045 erg s−1 in the (2-10) keV energy band. The cluster has an overall temperature of kT = 10.0 ± 0.3 keV and is not isothermal: the temperature profile shows a decline in the outer regions and a drop in the centre, indicating the presence of a cooling core. The spectral analysis identifies a hot region at radii 50-200 kpc to south-east (SE) of the main X-ray peak, at a position consistent with the subclump seen in the X-ray image. Excluding the data of the SE quadrant, the cluster appears relatively relaxed and we estimate a total mass within 1 Mpc of 1.0 ± 0.2 × 1015M⊙.