Many models of dark matter feature small scale substructure. In this talk, I will describe how gravitational microlensing provides stringent constraints on such models. In particular, I will explain how existing techniques used to probe point-like objects (such as primordial black holes and MACHOs) can be adapted to find constraints on several different extended objects. Optical effects such as caustics imply a sensitivity to the mass distribution of the particular object. I will describe how to account for the finite size of the source, important for light structures. Using data from EROS-II, OGLE, and Subaru-HSC experiments, constraints can then be found on the dark matter fraction bound up in compact structures.
Host: Jack Setford and David Curtin