Fundamental Cosmology with the Smallest Galaxies

Ultrafaint dwarf galaxies are the ghostly relics of an early phase of galaxy formation. Their distribution and formation history encode the physics of reionisation, while their abundance as satellites is strongly sensitive to the particular assembly history of the parent halo in which they are hosted. In this talk, I will present some of the ways in which the properties of the dwarf galaxy population can be connected with cosmological structure on larger scales, and how the statistics of their population can be used as important signatures of the nature of the dark matter particle.