Theory HEP Seminar

Quantum gravity corrections to absorption and emission of 4d near-extremal black holes in supergravity and Einstein gravity

Anna Biggs

Princeton

In the last decade, it has been understood that the spectrum and dynamics of near-extremal black holes receive quantum gravity corrections that become large at low temperatures. These corrections come from a soft mode in the near-horizon geometry that is strongly coupled at low energies and is governed by a Schwarzian action. In this talk, I will use solutions of the Schwarzian action to discuss how some observables of near-extremal 4d asymptotically flat black holes are modified. In particular, I will compare the Schwarzian-corrected scalar absorption cross sections and emission rates of nearly-BPS black holes in N = 2 supergravity to those of near-extremal black holes in Einstein gravity. The latter case was recently considered in arXiv:2411.03447. The two black holes behave very differently in the low temperature regime where quantum gravity effects are important, which can be attributed to the presence of a large ground state degeneracy and a gap in the density of states in the supersymmetric case. I will also discuss how the probability distribution of energy level occupation evolves with time due to Hawking radiation. Surprisingly, Schwarzian corrections cause the black hole to evolve to a non-thermal equilibrium state which is independent of the initial distribution.