A Hubble study pinpointed four main areas in the Abell 901/902 supercluster where dark matter has pooled into dense clumps. These areas match the location of hundreds of galaxies that have experienced a violent history in their passage from the outskirts of the supercluster into these dense regions. This image shows one of the four main areas.
NASA/ESA/C. Heymans/M. Gray/M. Barden/STAGES