2010MNRAS.403.1787L

We present photometric, spectroscopic and weak lensing analysis of the large-scale structure and dynamics of the most X-ray luminous galaxy cluster known, RX J1347-1145, at z = 0.451. We spectroscopically confirmed 47 new members with Low Dispersion Survey Spectrograph 3 (LDSS3) on the Magellan telescope. Together with previously known members, we measure a new velocity dispersion of 1163±97km/s. The mass inferred from our velocity dispersion is M₂₀₀= 1.16^+0.32_–0.27x10¹⁵M_☉, with r₂₀₀ = 1.85Mpc, under the assumption of a singular isothermal sphere. We also present a weak lensing analysis using deep Canada-France-Hawaii Telescope (CFHT) data on this cluster, and find a deprojected mass of 1.47^+0.46_–0.43 x10¹⁵M_☉ within r₂₀₀, in excellent agreement with our dynamical estimate. Thus, our new dynamical mass estimate is consistent with that from weak lensing and X-ray studies in the literature, resolving a previously claimed discrepancy. We photometrically detect and spectroscopically confirm another massive cluster with σ = 780±100km/s and M₂₀₀ = 3.4^+1.4_–1.1x10¹⁴M_☉∼ 7Mpc south-west of RX J1347-1145, which we refer to as RXJ1347-SW. Our spectroscopic survey reveals a possible excess of galaxies in velocity space in the region between RX J1347-1145 and RXJ1347-SW; comparing with simulations, this excess appears consistent with that expected from a large filamentary structure traced by galaxies connecting these two clusters.