Absorption by stringy black holes

TL;DR

This paper numerically analyzes how planar massless scalar waves are absorbed by Kerr--Sen black holes and compares the results with Kerr-Newman black holes, revealing similar absorption behaviors with differences growing at higher charge ratios.

Contribution

It provides the first detailed numerical comparison of scalar wave absorption between Kerr--Sen and Kerr-Newman black holes, highlighting their similarities and differences.

Findings

Absorption cross sections are similar for both black holes.

Differences increase with higher charge ratios.

Kerr--Sen black holes behave similarly to Kerr-Newman black holes in absorption.

Abstract

We investigate the absorption of planar massless scalar waves by a charged rotating stringy black hole, namely a Kerr--Sen black hole. We compute numerically the absorption cross section and compare our results with those of the Kerr-Newman black hole, a classical general relativity solution. In order to better compare both charged black holes, we define the ratio of the black hole charge to the extreme charge as $Q$. We conclude that Kerr--Sen and Kerr-Newman black holes have a similar absorption cross section, with the difference increasing for higher values of $Q$.