EFT corrections to scalar and vector quasinormal modes of rapidly rotating black holes

TL;DR

This paper uses effective field theory to compute leading order corrections to scalar and electromagnetic quasinormal modes of rapidly rotating Kerr black holes, revealing polarization-dependent frequency shifts.

Contribution

It introduces a general perturbative method to calculate EFT corrections to quasinormal modes for Kerr black holes of any spin, including parity even and odd electromagnetic cases.

Findings

Electromagnetic corrections split into two polarization families with opposite shifts.

Parity even and odd EFT corrections have identical spectra.

Results are validated through multiple consistency checks.

Abstract

Quasinormal modes characterize the final stage of a black hole merger. In this regime, spacetime curvature is high, these modes can be used to probe potential corrections to general relativity. In this paper, we utilize the effective field theory framework to compute the leading order correction to massless scalar and electromagnetic quasinormal modes. Proceeding perturbatively in the size of the effective field theory length scale, we describe a general method to compute the frequencies for Kerr black holes of any spin. In the electromagnetic case, we study both parity even and parity odd effective field theory corrections, and, surprisingly, prove that the two have the same spectrum. Furthermore, we find that, the corrected frequencies separate into two families, corresponding to the two polarizations of light. The corrections pertaining to each family are equal and opposite. Our results are validated through several consistency checks.