The Velocity Dispersion and X-Ray Structure of Abell 963
Abstract
Abell 963 (z = 0.2) is an X-ray luminous, centrally concentrated cluster of galaxies with a dominant central cD galaxy. A963 also has two large diametrically opposed gravitational arcs associated with it, for which the origin from a single background galaxy is still uncertain. We will present the results from two observational programs on A963: 1) Redshifts have been obtained for a total of 79 objects in the field of A963, consisting of 56 clusters members, 21 galaxies which are either foreground or background, and 2 galactic stars. We have used a subset of 36 red cluster members, for which spectra were obtained during a single observing run, to determine the cluster velocity dispersion. We find a value of ~ 1350 km s(-1) (+200,-150) for sigma _r, the rest-frame radial velocity dispersion, which is similar to other known lensing clusters. 2) ROSAT HRI observations of A963 reveal the cluster X-ray gas to be centrally concentrated and ellipsoidal rather than spherical in shape. Preliminary values for the core radius, r_c, and the ellipticity, epsilon , are ~ 25'' and ~ 0.25, respectively. While this ellipticity is less than that of the central cD galaxy, which has epsilon = 0.5, the X-ray gas and the cD galaxy are aligned along the same axis.
- Publication:
-
American Astronomical Society Meeting Abstracts #192
- Pub Date:
- May 1998
- Bibcode:
- 1998AAS...192.3703L