Abstract:

The nature of dark matter remains a profound problem in our understanding of the universe. Though the census of dark matter is fairly robust, the plausible range of properties that a candidate particle may have is broad enough to allow for many possibilities. The distinctions between candidates may manifest themselves at relatively modest astrophysical mass-scales, which may be probed by strong gravitational lensing, uniquely so at cosmological distances. Complementary observations of even a single strong lens can probe different moments of the "substructure" mass function, over a very large range of mass-scales. I will present the theory of substructure probes in lenses, including new work on time-delay perturbation studies, and will discuss the power of current and future observations (and the need for new concrete theoretical predictions) for tackling the problem of dark matter. This work leads to a new mission concept that would be dedicated to this goal.>