Greybody Factors for Brane Scalar Fields in a Rotating Black-Hole Background

TL;DR

This paper analyzes the absorption probabilities and cross-sections of scalar fields around rotating higher-dimensional black holes, providing analytic solutions in both low and high-energy regimes that align well with numerical data.

Contribution

It introduces new analytic methods for calculating greybody factors of brane scalar fields in rotating black-hole backgrounds across energy regimes.

Findings

Analytic low-energy absorption probabilities match numerical results.

High-energy analytic solutions agree with numerical data.

High-energy cross-section approaches the geometrical optics limit.

Abstract

We study the evaporation of (4+n)-dimensional rotating black holes into scalar degrees of freedom on the brane. We calculate the corresponding absorption probabilities and cross-sections obtaining analytic solutions in the low-energy regime, and compare the derived analytic expressions to numerical results, with very good agreement. We then consider the high-energy regime, construct an analytic high-energy solution to the scalar-field equation by employing a new method, and calculate the absorption probability and cross-section for this energy regime, finding again a very good agreement with the exact numerical results. We also determine the high-energy asymptotic value of the total cross-section, and compare it to the analytic results derived from the application of the geometrical optics limit.