1999ApJ...522...39T

We present results from a dynamical study of the high-redshift, massive, X-ray-luminous galaxy cluster MS 1054-03. We significantly increase the number of confirmed cluster members by adding 20 to an existing set of 12; using the confirmed members, we estimate MS 1054-03's redshift, velocity dispersion, and mass. We find that z=0.8329±0.0017, σ=1170±150 km.s^–1, and the central mass is approximately 1.9±0.5x10¹⁵ h^–1 M_☉ (within R=1 h^–1 Mpc; H₀=100 h km.s^–1.Mpc^–1, q₀=0.5). MS 1054-03 is one of a handful of high-redshift (z>0.5) clusters known that also has X-ray and weak-lensing observations; we find our dynamical mass agrees with mass estimates from both studies. The confirmation of MS 1054-03 as a massive cluster at z∼0.8 is consistent with an open (Ω_M∼0.3) or flat, Λ-dominated (Ω_M+Ω_Λ=1) universe. In addition, we compare MS 1054-03's velocity dispersion and X-ray temperature to a sample of low- and intermediate-redshift galaxy clusters to test for evolution in the σ-T_X relation; we find no evidence for evolution in this relation to z∼0.8.