Evolution of near extremal black holes

TL;DR

This work investigates near-extremal five-dimensional Reissner–Nordström black holes, computing greybody factors for low-energy neutral and charged scalar emission to compare decay channels. By solving the Klein–Gordon equation and matching near/far regions, the authors derive absorption cross-sections and emission rates, finding that the ratio of charged-to-neutral energy loss is moduli independent and depends only on integral charges and horizon potentials. Neutral emission generally dominates near extremality unless one charge is very light or vastly larger than the others; charged emission becomes significant only in narrow parameter regimes, indicating a universal structure in near-extremal black-hole scattering. The results illuminate the relationship between black-hole and D-brane emission rates and contribute to discussions on information loss, while also showing similar modular independence in four dimensions.

Abstract

Near extreme black holes can lose their charge and decay by the emission of massive BPS charged particles. We calculate the greybody factors for low energy charged and neutral scalar emission from four and five dimensional near extremal Reissner-Nordstrom black holes. We use the corresponding emission rates to obtain ratios of the rates of loss of excess energy by charged and neutral emission, which are moduli independent, depending only on the integral charges and the horizon potentials. We consider scattering experiments, finding that evolution towards a state in which the integral charges are equal is favoured, but neutral emission will dominate the decay back to extremality except when one charge is much greater than the others. The implications of our results for the agreement between black hole and D-brane emission rates and for the information loss puzzle are then discussed.