Speaker: Christian Byrnes (Uni of Sussex)
Title: Primordial Black Holes: Fine-tuning and fine opportunities
Abstract: I will discuss the extreme sensitivity of the primordial black hole (PBH) number density to changes in the inflationary model which could have generated them – showing that at least one of the most popular methods for generating PBHs requires substantial fine-tuning. However, there is an interesting coincidence of scales between the black hole merger events seen by LIGO-Virgo-KAGRA, the Chandrasekhar limit, the horizon mass during the QCD transition in the early universe, and the wavelength of gravitational waves on which NANOGrav may (potentially) have detected a stochastic gravitational wave background. This provides a great opportunity for a robust PBH detection soon, if they exist in this mass range.