Dark Matter Energy Deposition and Production from the Table-Top to the
  Cosmos
  The discovery of nongravitational interactions between dark matter and the
Standard Model would be an important step in unraveling the nature of dark
matter. If such an interaction exists, it would have profound implications on
how dark matter is produced in both the early universe and in collider
experiments. In addition, it would also allow dark matter to deposit energy
into Standard Model particles in unexpected ways. This thesis details some
recent progress made in understanding these implications, including (i) a new
freezeout mechanism for thermal dark matter dominated by a 3-to-2 process
within a vector portal dark sector model; (ii) a study of how the existence of
dark sector bound states can influence collider, direct and indirect searches
for dark matter; (iii) a new axion dark matter interferometric search using a
cavity that is sensitive to the axion-induced rotation of linearly polarized
light; (iv) a definitive assessment of the potential contribution of dark
matter annihilation and decay to cosmic reionization; (v) new constraints on
dark matter annihilation rates and decay lifetimes from 21-cm cosmology, and
(vi) a new numerical code, DarkHistory, which significantly improves the
computation of the ionization and thermal histories of the universe in the
presence of exotic sources of energy injection. These novel ideas span length
scales ranging from table-top experiments to the entire cosmos, and represent
just a few of the myriad of ways in which dark matter may yet surprise us.
