Probing higher curvature gravity via ringdown with overtones

TL;DR

This paper studies how higher curvature gravity modifies black hole ringdown signals, especially overtone quasinormal modes, and demonstrates that these deviations can be detected through waveform analysis.

Contribution

It reveals how higher curvature corrections affect black hole quasinormal modes and shows their potential observability in gravitational wave signals.

Findings

Higher curvature terms deform the near-horizon potential and shift QNM frequencies.

Deviations from GR become more significant for overtone modes as curvature order increases.

Shifted QNMs can be identified in ringdown waveforms via waveform fitting.

Abstract

We investigate metric perturbations of a spherically symmetric black hole in higher curvature gravity. We show that higher curvature corrections deform the near-horizon region of the effective potential, and that the deviations of the quasinormal mode (QNM) frequencies from their general relativity (GR) values become more pronounced for overtone modes. We find that, as the order of the higher curvature term increases, the deformations approach the horizon and the deviations of the overtone QNM frequencies grow progressively larger. We also analyze the ringdown waveforms in the higher curvature gravity model. We consider setups in which the deviations from the vacuum-GR QNMs remain mild for the fundamental mode and the first few overtones, and show that these shifted QNMs can be identified in the ringdown signal through waveform fitting.