Hubble image of galaxy cluster Abell 3827 showing dark matter distribution

This image from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 3827. The strange pale blue structures surrounding the central galaxies are gravitationally lensed views of a much more distant galaxy behind the cluster.

The distribution of dark matter in the cluster is shown with blue contour lines. The dark matter clump for the galaxy at the left is significantly displaced from the position of the galaxy itself, possibly implying dark matter-dark matter interactions of an unknown nature are occuring.