Cosmological probes of the early Universe offer a powerful way to test dark matter scenarios that modify its thermal and ionization history. The cosmic microwave background already places some of the strongest constraints on models involving exotic energy injection, while upcoming 21-cm observations promise a new window into the cosmic dawn and the epoch of reionization. These measurements are also sensitive to the uncertain properties of the first stars and galaxies, making the interpretation of dark matter signatures especially challenging.
In this talk, I will review current cosmic microwave background constraints on annihilating dark matter and primordial black holes, and then discuss how astrophysical uncertainties impact forecast constraints from the 21-cm signal.
Ana Martín Galán and Francesco Paolo Di Meglio