SUBSTRUCTURE - CLUES TO THE FORMATION OF CLUSTERS OF GALAXIES

We have examined the spatial distribution of substructure in clusters of galaxies using Einstein X-ray observations. Subclusters are found t o have a markedly anisotropic distribution that reflects the surroundi ng matter distribution on supercluster scales. Our results suggest a p icture in which cluster formation proceeds by mergers of subclusters a long large-scale filaments. The implications of such an anisotropic fo rmation process for the shapes, orientations, and kinematics of cluste rs are discussed briefly.