The Quasinormal Modes of Quasinormal Modes

TL;DR

This paper explores how modifications near black hole horizons affect quasinormal modes, showing that near-horizon changes have minimal impact on observable ringdown signals and that original modes can be reconstructed from new ones.

Contribution

It demonstrates the emergence of original quasinormal modes from the sum over modified modes in near-horizon black hole scenarios.

Findings

Near-horizon modifications minimally alter ringdown signals

Original quasinormal modes can be reconstructed from modified spectra

The spectrum remains well-described by original modes despite modifications

Abstract

Modifying black hole horizon can drastically change the spectrum of quasinormal modes. But if the modification is close enough to the horizon the ringdown signal remains almost unaltered, and well described by the quasinormal modes of the original GR solution. I show how the original quasinormal modes emerge in the sum over the new modes.