Massive scalar quasinormal modes of an asymptotically flat regular black hole supported by a phantom Dirac--Born--Infeld field

TL;DR

This study analyzes the quasinormal modes of a massive scalar field around a regular black hole supported by a phantom Dirac--Born--Infeld field, revealing how mass and regularity affect oscillation and damping.

Contribution

It provides the first detailed computation of massive scalar quasinormal modes in this specific regular black hole geometry using advanced numerical methods.

Findings

Increasing field mass raises oscillation frequency and reduces damping.

Higher regularity makes the ringing softer and longer-lived.

Large field mass leads to quasiresonant modes with near-zero damping.

Abstract

We study the quasinormal spectrum of a massive test scalar field in the exact asymptotically flat regular black-hole geometry supported by a phantom Dirac--Born--Infeld scalar. Using high-order WKB approximation improved by Pad\'e resummation, together with characteristic time-domain integration and Prony extraction, we compute the fundamental mode and the first two overtones for representative values of the regularity parameter and the field mass. We show that increasing the field mass raises the oscillation frequency and reduces the damping rate, while increasing the regularity scale generally makes the ringing softer and longer lived. The time-domain profiles are in very good agreement with the WKB--Pad\'e results and confirm the robustness of the spectrum. For sufficiently large field mass, the damping tends to zero, indicating the onset of quasiresonant behavior, although in the time domain these modes are eventually masked by oscillatory late-time tails. Our results show that massive scalar ringing provides a sensitive probe of this DBI-supported regular geometry.