Dynamical Friction in the Coma Cluster

Abstract

If the galaxies composing the Coma Cluster were initially ‘Ostriker-Peebles’ galaxies (i.e., isothermal spheres extending to 250–500 kpc), the hidden mass is likely to be tidally torn-off halos. Owing to dynamical friction, the remnant cores tend to spiral in to the center of the cluster. This happens as long as the hidden mass, whatever its origin, consists of objects much less massive than galaxies.