The Spatial Distribution, Kinematics, and Dynamics of the Galaxies in the Region of Abell 2634 and 2666

Abstract

A total of 663 galaxies with known redshifts in a $6°\!\times 6°$ field centered on A2634, including 211 new measurements, are used to study the structure of this cluster and its surroundings. Two samples, ---one containing 200 galaxies within two degrees from the cluster center and a second, magnitude-limited, of 118 galaxies within the central half degree---, are used to examine the structure, kinematics, dynamics of A2634. We show that early-type galaxies appear to be a relaxed system, while the spiral population eschews the center of the cluster and exhibits both a multimodal velocity distribution and a much larger velocity dispersion than the ellipticals. We find no evidence of significant substructure in the central regions supportive of a recent merger of two subclusters, a scenario that has been suggested to explain the bending of the tails of the cluster central radio source (3C 465). We also conclude that the adoption of lenient membership criteria that ignore the dynamical complexity of A2634 are unlikely to be responsible for the conflictual results reported on the motion of this cluster with respect to the CMB. The kinematical and dynamical analysis is extended to A2634's close companion, A2666, and to two distant background clusters at 18,000 and 37,000 $\rm km s^{-1}$.