The large mass of a galaxy cluster deflects light from background objects, a phenomenon known as gravitational lensing. The large-scale gravitational lens caused by the whole cluster can be modified by smaller-scale mass concentrations within the cluster, such as individual galaxies. Using the NASA/ESA Hubble Space Telescope and ESO’s Very Large Telescope (VLT), a team of astronomers has examined these small-scale gravitational lenses in 11 galaxy...
