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[64.03] A Mass and H₀ Estimate from Sunyaev-Zel'dovich Effect, X-ray, and Optical Measurements of Galaxy Cluster Abell 1995

S. K. Patel (U. Alabama in Huntsville), M. Joy (NASA/MSFC), J. Carlstrom, G. Holder, E. Reese (U. Chicago), P. Gomez, J. Hughes (Rutgers U.), L. Grego (CfA-SAO), W. Holzapfel (UC Berkeley)

We present X-ray and Sunyaev-Zel'dovich Effect imaging, X-ray spectroscopy, and optical spectroscopy of the galaxy cluster Abell 1995. From these measurements, we determine several physical parameters of the cluster: an accurate redshift [0.3219±.0014], galaxy velocity dispersion [1282⁺¹⁵³_-120 km s^-1], core radius [32.5^+2.9_-4.3 arcsec], electron temperature [8.59^+0.86_-0.67 keV], and central electron number density [1.23^+0.20_-0.10 \times 10^-2 h₁₀₀^1/2 cm^-3]. The X-ray and Sunyaev-Zel'dovich Effect observations are combined to determine the cluster distance [D_A=1241 Mpc ⁺²⁶⁰_-252(statistical) ⁺⁴⁰⁷_-551(systematic)], and hence yield a measure of the Hubble constant [H₀=50.3 km s^-1 Mpc^{-1 +10.2}_-10.9(statistical) ^+22.3_-16.7 (systematic)]. The X-ray data and optical velocity dispersion are also used to derive independent and consistent estimates of the total mass of the cluster, which are then combined with gas mass measurements to place constraints on the cluster gas fraction and baryon fraction.