The distance and mass of the galaxy cluster Abell 1995 derived from Sunyaev-Zeldovich effect and X-ray measurements

We present multiwavelength observations of the Abell 1995 galaxy cluster. F rom an analysis of X-ray spectroscopy and imaging data, we derive the elect ron temperature, cluster core radius, and central electron number density. Using optical spectroscopy of 15 cluster members, we derive an accurate clu ster redshift and velocity dispersion. Finally, the interferometric imaging of the Sunyaev-Zeldovich effect toward Abell 1995 at 28.5 GHz provides a m easure of the integrated pressure through the cluster. The X-ray and Sunyae v-Zeldovich effect observations are combined to determine the angular diame ter distance to the cluster of D-A = 1294(-283)(-458)(+294)(+438) Mpc (stat istical followed by systematic uncertainty), implying a Hubble constant of H-0 = 52.2 (+11.4)(+18.5)(-11.9)(-17.7) km s(-1) Mpc(-1) for Ohm(M) = 0.3 a nd Ohm(Lambda) = 0.7. We find a best-fit H-0 of 46 km s(-1) Mpc(-1) for the Ohm(M) - 1 and Ohm(Lambda) = 0 cosmology, and 48 km s(-1) Mpc(-1) for = 0. 3 and Ohm(Lambda) = 0.0. The X-ray data are also used to derive a total clu ster mass of M-tot(HSE)(r(500)) = 5.18(-0.48)(+0.62) x 10(14) h(-1) M.; the optical velocity dispersion yields an independent and consistent estimate of M-tot(virial)(r(500)) = 6.35(-1.19)(+1.51) X 10(14) h(-1) M.. Both of th e total mass estimates are evaluated at a fiducial radius, r(500) = 830 h(- 1) kpc, where the overdensity is 500 times the critical density. The total cluster mass is then combined with gas mass measurements to determine a clu ster gas mass fraction of f(g) = 0.056(-0.013)(+0.010)h(-3/2). In combinati on with recent baryon density constraints, the measured gas mass fraction y ields an upper limit on the mass density parameter of Ohm(M) h(1/2) less th an or equal to 0.34(-0.05)(+0.06).