Quasinormal modes of Schwarzschild-like black hole surrounded by the pseudo-isothermal dark matter halo

TL;DR

This paper studies how dark matter halos influence the quasinormal modes of Schwarzschild-like black holes, revealing their impact on gravitational wave signals and the black hole shadow through numerical analysis.

Contribution

It introduces a detailed numerical analysis of scalar perturbations and explores the connection between black hole shadows and QNMs in dark matter environments.

Findings

Dark matter halos alter the quasinormal mode frequencies.

The black hole shadow is affected by surrounding dark matter.

A link between QNMs and black hole shadows is established.

Abstract

The merger of binary black holes produces a series of decaying oscillations, during which energy is radiated in gravitational waves. The characteristic signal in the ringdown phase can be described by complex oscillation frequencies called quasinormal modes (QNMs). In this paper, we investigate the ringdown spectrum resulting from scalar field perturbations of black holes surrounded by pseudo-isothermal dark matter halos. The complex frequencies of these quasinormal modes are numerically computed using the sixth-order WKB approximation. Additionally, the time evolution of the scalar perturbations is examined using the finite difference method, considering various multipole numbers and dark matter halo parameters. For a static, spherically symmetric black hole, the photon sphere--composed of circular null geodesics--plays a crucial role in analyzing the black hole shadow. Furthermore, the connection between the black hole shadow and QNMs is explored in the eikonal limit.