Gravitational Lensing in Galaxy Cluster Abell 1689
b'Abell 1689 is a massive galaxy cluster that has an impressive number of gravitationally lensed background galaxies. In this thesis more than 30 multiple image systems identified in A1689 are used to derive an accurate mass profile for the cluster. It is also shown how strong lensing in cluster can be used to constrain the sizes of the dark matter haloes of cluster galaxies and to place upper limits on the amount of dark substructure in clusters.'