The velocity dispersion of MS 1054-03:A massive galaxy cluster at high redshift

We present results from a dynamical study of the high-redshift, massive, X-ray-luminous galaxy duster 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, sigma = 1170 +/- 150 km s(-1), and the central mass is approximately 1.9 +/- 0.5 x 10(15) h(-1) M. (within R = 1 h(-1) Mpc; H-0 = 100 h km s(-1) Mpc(-1), q(0) = 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 similar to 0.8 is consistent with an open (Omega(M) similar to 0.3) or flat, Lambda-dominated (Omega(M) similar to Omega(Lambda) = 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 sigma-T-X relation; we find no evidence for evolution in this relation to z similar to 0.8.