2008A&A...481...65H

We determine the central mass distribution of galaxy cluster RX J1347-1145 using strong gravitational lensing. High-resolution HST/ACS images of the galaxy cluster RX J1347-1145 have enabled us to identify several new multiple-image candidates in the cluster, including a 5-image system with a central image. The multiple-images allow us to construct an accurate 2-dimensional mass map of the central part of the cluster. The modelling of the cluster mass includes the most prominent cluster galaxies modelled as truncated isothermal spheres and a smooth halo component that is described with 2 parametric profiles. The mass reconstruction is done using a Markov chain Monte Carlo method that provides us with a total projected mass density, as well as with estimates for the parameters of interest and their respective errors. Inside the Einstein radius of the cluster (∼35", or ∼200kpc, for a source at redshift 1.8), we obtain a total mass of (2.6±0.1)x10¹⁴M_☉. The mass profile of the cluster is well-fitted by both a Navarro, Frenk, and White profile with a moderate concentration of c=5.3^+0.4_–0.6 and r₂₀₀=3.3^+0.2_–0.1Mpc, and a non-singular isothermal sphere with velocity dispersion σ=1949±40km/s and a core radius of r_c=20±2". The mass profile agrees with previous mass estimates based on the X-ray emission from the hot intra-cluster gas, although the X-ray mass estimates are systematically lower than what we obtain with gravitational lensing.