Abstract :
Gravitational lensing provides a direct, purely gravitational means to detect low-mass (<10^8 solar mass) dark matter halos at cosmological distance. If cold dark matter (CDM) is correct, large populations of these dark objects must exist, while alternative dark matter theories, such as warm and self-interacting dark matter, alter their abundance and internal structure relative to CDM. I will describe the background and latest developments in the use of strong gravitational lensing to detect and characterize the properties of dark substructure, and what these analyses reveal about the fundamental nature of dark matter.
