Dynamics and shape of brightest cluster galaxies

Abstract

We identified Brightest Cluster Members (BCM) on DSS images of 1083 Abell clusters, derived their individual and host cluster redshifts from literature and determined the BCM ellipticity. Half the BCMs move at a speed higher than 37% of the cluster velocity dispersion scl, suggesting that most BCMs are part of substructures falling into the main cluster. Both, the BCM's velocity offset in units of σcl, and BCM ellipticity, weakly decrease with cluster richness. © 2007 Springer.