The Mass distribution of the Most Luminous X-ray Cluster RXJ1347.5-1145 from Gravitational Lensing

Galaxy cluster mass distribution are potentially useful probes of Ω0 and the nature of the dark matter. Large clusters will distort the observed shapes of background galaxies through gravitational lensing allowing the measurement of the cluster mass distributions. In this paper we describe weak statistical lensing measurements of the most luminous X-ray cluster known, RXJ1347.5-1145 at z = 0.45. We detect a shear signal in the background galaxies at a signalto-noise ratio of 7.5 in the radial range 120 ≤ r ≤ 1360h kpc. A mass map of the cluster reveals an 11σ peak in the cluster mass distribution consistent with the position of the central dominant galaxy and 3 σ evidence for the presence of a subcluster at a projected radius of 1.3 1.7 h Mpc from the cluster center. In the range 120 ≤ r ≤ 1360h kpc mass traces light, and the azimuthally averaged cluster mass and light profiles are consistent with singular isothermal spheres with M(r < 1 Mpc) = 1.7± 0.4× 10 M⊙. Assuming an isotropic velocity distribution function, the implied velocity dispersion is σ = 1500± 160 km s. The rest-frame mass-to-light ratio is M/LB = 200 ± 50h M⊙/LB⊙. The lensing mass estimate is almost twice as high as a previously determined X-ray mass estimate.