Discovering the Particle Physics of Dark Matter with Cosmology

The study of cosmology has so far been a powerful probe of the macroscopic properties of dark matter. In this talk, I will discuss how we can build on the successes of cosmology to also uncover the microscopic properties of dark matter, especially the existence of any nongravitational interaction between dark matter and regular matter. I will describe what a wide range of current and near-future cosmological probes can broadly tell us about the particle physics of dark matter, focusing on the particularly interesting example of ultralight dark photons---various cosmological probes offer remarkable sensitivity to, and even hints of, the existence of such particles.