Scalar, electromagnetic, and Dirac perturbations of regular black holes constituting primordial dark matter

TL;DR

This paper investigates how regular black holes supported by a phantom scalar field influence the quasinormal modes of scalar, electromagnetic, and Dirac perturbations, revealing a spin-dependent spectral shift.

Contribution

It introduces a detailed analysis of quasinormal frequencies for regular black holes with a Dirac--Born--Infeld scalar, highlighting the impact of regularity on ringdown spectra.

Findings

Larger regularity shifts the spectrum toward lower frequencies and damping rates.

The quality factor is only weakly affected by regularity.

Spectral shifts are significant and above numerical uncertainties, indicating a robust imprint.

Abstract

We study massless scalar, electromagnetic, and Dirac perturbations of the exact asymptotically flat regular black hole supported by a phantom Dirac--Born--Infeld scalar. Using the Pad\'e-improved WKB method, with a time-domain Prony check for the scalar fundamental mode, we compute representative quasinormal frequencies and find that larger regularity shifts the spectrum toward smaller oscillation frequencies and damping rates, whereas the quality factor changes only weakly. The spectral shifts remain well above the estimated numerical uncertainty, demonstrating that the DBI regularity scale leaves a robust spin-dependent imprint on ringdown.