Quasinormal modes and grey-body factors of axial gravitational perturbations of regular black holes in asymptotically safe gravity

TL;DR

This paper investigates axial gravitational perturbations of regular black holes in asymptotically safe gravity, computing quasinormal modes with high accuracy and analyzing grey-body factors, revealing deviations from Schwarzschild black holes at higher overtones.

Contribution

It introduces precise numerical methods to analyze QNMs of regular black holes in asymptotically safe gravity, highlighting deviations at higher overtones and confirming grey-body factor and QNM correspondence.

Findings

Fundamental mode weakly affected by deviation parameter.

Higher overtones show notable deviations from Schwarzschild case.

Grey-body factors agree well with QNM calculations, especially at larger l.

Abstract

In this paper, we present a detailed study of axial gravitational perturbations of the regular black hole solution in asymptotically safe gravity, as proposed in \cite{Bonanno:2023rzk}. We analyze the quasinormal mode (QNM) spectrum of this black hole using two numerical techniques: the Bernstein spectral method and the asymptotic iteration method (AIM). These approaches allow us to compute QNM frequencies with high accuracy, even for higher overtones. Our results show that the fundamental mode is only weakly affected by the deviation parameter, whereas notable deviations from the Schwarzschild case emerge for higher overtones. Additionally, we examine the correspondence between grey-body factors and QNMs using the sixth-order WKB approximation, finding excellent agreement, especially for larger multipole numbers l.