Absorption of scalars by nonextremal charged black holes in string theory

TL;DR

This paper investigates how minimally coupled massless scalar fields are absorbed by various charged black holes in string theory, revealing a universal temperature-dependent cross section that remains finite in the extremal limit, including with string corrections.

Contribution

It demonstrates that the low frequency absorption cross section of scalar fields by charged black holes universally depends on parameters divided by the Hawking temperature, even with string alpha' corrections.

Findings

Cross section proportional to solution parameter over Hawking temperature

Finite cross section in the extremal limit despite temperature dependence

String alpha' corrections induce the same temperature dependence

Abstract

We analyze the low frequency absorption cross section of minimally coupled massless scalar fields by different kinds of charged static black holes in string theory, namely the D1-D5 system in d=5 and a four dimensional dyonic four-charged black hole. In each case we show that this cross section always has the form of some parameter of the solution divided by the black hole Hawking temperature. We also verify in each case that, despite its explicit temperature dependence, such quotient is finite in the extremal limit, giving a well defined cross section. We show that this precise explicit temperature dependence also arises in the same cross section for black holes with string alpha' corrections: it is actually induced by them.