Quasinormal Modes and Grey-Body Factors of Scalar, Electromagnetic and Dirac Fields Around Einasto-Supported Regular Black Holes

TL;DR

This paper investigates how matter distribution according to the Einasto profile affects quasinormal modes and grey-body factors of various fields around regular black holes, revealing that the environment influences oscillation frequencies and damping rates.

Contribution

It provides the first detailed analysis of quasinormal modes and grey-body factors for black holes with Einasto matter distribution, using high-order WKB and time-domain methods.

Findings

Quasinormal modes are close to Schwarzschild values for small Einasto indices.

Oscillation frequencies increase and damping decreases with halo parameter for larger indices.

Grey-body factors show mild suppression at low frequencies due to the halo environment.

Abstract

We study quasinormal modes and grey-body factors of scalar, electromagnetic and Dirac test fields for a black hole surrounded by matter distributed according to the Einasto density profile. The quasinormal spectrum is calculated using the high-order WKB method with Pad\'e approximants and checked by the time-domain integration. For small values of the Einasto index $\tilde n=1/2$ and $\tilde n=1$, the fundamental modes remain close to their Schwarzschild values, while for $\tilde n=5$ the oscillation frequency increases and the damping rate decreases as the halo parameter grows. Grey-body factors are much less sensitive to the halo environment: the main effect is a mild suppression at low frequencies caused by a moderate increase of the effective potential near the horizon. At higher frequencies the transmission probabilities remain close to the Schwarzschild case.