Scalar absorption cross section of rotating black holes with tidal charge

TL;DR

This paper calculates the scalar wave absorption cross section of rotating black holes with tidal charge in a brane-world scenario, revealing how the cross section varies with black hole parameters and frequency regimes.

Contribution

It provides the first detailed analysis of scalar absorption cross sections for rotating black holes with tidal charge, considering various incidence angles and near-extreme conditions.

Findings

Absorption cross section increases with more negative tidal charge near extremality.

Black holes with different configurations can have identical shadow sizes but different spectra.

High-frequency limits match capture cross sections; low-frequency limits match black hole area.

Abstract

The absorption cross section of rotating black holes in the Randall-Sundrum brane-world scenario for massless scalar waves is obtained via the partial-wave method. A variety of incidence directions with respect to the black hole rotation axis is considered. Special attention is given to near-extreme black holes, in which cases the absorption cross section increases as the tidal charge becomes more negative. It is shown that black holes with different configurations can present capture cross sections/shadows of same size. However, in such cases, the absorption spectra are different mainly for small frequencies. Numeric results are compared with the capture cross sections in the high-frequency limit, and with the black hole area in the low-frequency limit showing good agreement.