Scattering by deformed black holes

TL;DR

This paper explores how scalar waves scatter and are absorbed by deformed black holes using various analytical and numerical methods, providing insights into deviations from classical black hole models.

Contribution

It introduces a formalism for analyzing scalar wave interactions with non-Schwarzschild black holes using deformation parameters and compares different approximation methods.

Findings

Excellent agreement between numerical and classical/scattering results.

Demonstrates the impact of deformation parameters on scattering cross sections.

Provides a framework for studying strong field regimes in alternative gravity theories.

Abstract

Obtaining black hole solutions in alternative theories of gravity can be a difficult task due to cumbersome field equations that arise in many of such theories. In order to study the strong field regime in a model-free approach, one can consider deformed black hole solutions with additional parameters beyond mass, charge and angular momentum. We investigate the scattering and absorption of a massless scalar field by non-Schwarzschild black holes, considering the Johannsen and Psaltis parametrization. In particular, we study the scattering process by the classical (null geodesics analysis), semiclassical (glory approximation) and partial waves approaches. We present the formalism needed to compute the scattering and absorption of massless scalar waves by Schwarzschild-like black holes with a set of deformation parameters in addition to their mass and present a selection of our results. We compare our numerical results for the scattering cross section with the classical and semiclassical results, obtaining excellent agreement.