Ringdown of a black hole embedded in a Burkert dark matter halo

TL;DR

This paper models a black hole within a Burkert dark matter halo, analyzing how the halo's properties affect black hole ringdown signals and providing benchmarks for gravitational wave tests of dark matter environments.

Contribution

It introduces a new static black hole solution embedded in a Burkert dark matter halo and studies its quasinormal modes using multiple computational methods.

Findings

Increasing halo core radius or density shifts frequencies upward and increases damping.

Multipole index primarily affects oscillation frequency with mild impact on decay.

High agreement between different frequency extraction methods.

Abstract

We construct a new static, spherically symmetric black hole spacetime embedded in a dark matter halo whose density follows the cored Burkert profile. Starting from the halo-only geometry determined by the rotation curve relation, we solve the Einstein equations with the Burkert stress-energy and enforce a Schwarzschild boundary condition, obtaining closed form metric functions in which the halo contribution deforms the redshift or shape functions and reduces to the Schwarzschild limit when the halo parameters vanish. On this background we study linear perturbations of test fields with spins $s=0,1,2$ and compute their quasinormal spectra using both a high order WKB scheme and continued fraction method, complemented by time domain evolutions. We find that increasing either the Burkert core radius $r_0$ or the central density $\rho_0$ generically shifts the real part of the frequencies upward and enhances damping, while the multipole index $l$ primarily increases the oscillation frequency with a milder impact on the decay rate. The two frequency extraction methods agree to within small, systematic offsets across the explored parameter space. Our results quantify how a cored dark matter environment imprints itself on the ringdown of a central black hole and provide benchmarks for future gravitational wave tests of halo properties.