Speaker
Description
Various cosmological scenarios give rise to primordial black holes in the early universe. If these black holes were light enough ($\lesssim 10^8$ g), they would have disappeared before BBN due to Hawking evaporation. Thus, their abundance is only weakly constrained by observations. Even if the abundance was small, the universe could have gone through an era of black-hole domination before they evaporated, in which case the hot plasma that seeded nucleosynthesis was reheated entirely from their evaporation. I will introduce Hawking relics: stable, dark-sector particles produced alongside the Standard Model by Hawking evaporating primordial black holes. If massive, these relics would act as warm dark matter, suppressing the growth of structure. I will show that Hawking relics are produced with much larger momenta, but in smaller quantities than the familiar thermal relics considered in standard cosmology. Consequently, Hawking relics with keV–MeV masses affect cosmology in a similar way to eV-scale thermal relics like massive neutrinos. I will discuss how the detailed momentum distribution generated by Hawking evaporation gives these relics a distinctive signature in the matter power spectrum. Finally, I will introduce new constraints on the fraction of dark matter in Hawking relics from cosmological data.
