Singularities of regular black holes and the monodromy method for asymptotic quasinormal modes

TL;DR

This paper uses the monodromy method to analyze the asymptotic quasinormal modes of regular black holes, revealing that their frequency spectrum depends on complex singularities and solution trajectories, not on the multipole number.

Contribution

It introduces a detailed analysis of regular black hole quasinormal modes using Stokes portraits, highlighting non-universality in their asymptotic spectra.

Findings

Asymptotic frequencies depend on complex singularities.

Spectrum is independent of multipole number.

Analytical forms vary with solution trajectories.

Abstract

We use the monodromy method to investigate the asymptotic quasinormal modes of regular black holes based on the explicit Stokes portraits. We find that, for regular black holes with spherical symmetry and a single shape function, the analytical forms of the asymptotic frequency spectrum are not universal and do not depend on the multipole number but on the presence of complex singularities and the trajectory of asymptotic solutions along the Stokes lines.