Speaker
Description
Gravitational wave observations have opened a direct route to studying black hole (BH) populations. In principle, primordial and astrophysical BHs may be distinguishable through their mass, spin, redshift, and merger-rate distributions. At the same time, the observed BH population provides a new probe of nuclear and particle physics in stellar cores. A major obstacle is that the late evolution of heavy stars remains insufficiently understood, especially near and above the predicted BH mass gap. I will discuss stellar evolution simulations of very massive BH progenitors, focusing on how predicted remnant masses and spins depend on uncertain assumptions. I will also discuss some recent observations which have challenged our understanding of how the most massive BHs form.