New Generic Ringdown Frequencies at the Birth of a Kerr Black Hole

TL;DR

This paper introduces a new ringdown frequency mode for Kerr black holes, derived from vacuum perturbations, which enhances understanding of black hole oscillations at formation.

Contribution

The study identifies and characterizes a novel ringdown frequency mode in Kerr black holes, expanding the spectrum of known oscillation modes at black hole birth.

Findings

Discovery of a new ringdown frequency mode.

Successful fitting of waveforms with the new mode.

Comparison with previous radiation studies.

Abstract

We discuss a new ringdown frequency mode for vacuum perturbations of the Kerr black hole. We evolve initial data for the vacuum radial Teukolsky equation using a near horizon approximation, and find a frequency mode analogous to that found in a recent study of radiation generated by a plunging particle close to the Kerr horizon. We discuss our results in the context of that study. We also explore the utility of this mode by fitting a numerical waveform with a combination of the usual quasi-normal modes (QNMs) and the new oscillation frequency.