Quasi-normal modes of rotating black holes in Einstein-dilaton Gauss-Bonnet gravity: the first order in rotation

TL;DR

This paper calculates the quasi-normal modes of rotating black holes in Einstein-dilaton Gauss-Bonnet gravity, revealing that rotation amplifies deviations from general relativity, aiding gravitational tests of modified gravity theories.

Contribution

It provides the first computation of rotating black hole quasi-normal modes in Einstein-dilaton Gauss-Bonnet gravity, including first-order spin effects.

Findings

Rotation significantly magnifies deviations in mode frequencies.

First-order in spin calculations for these black holes.

Potential for improved gravitational tests of modified gravity.

Abstract

Gravitational spectroscopy - the measurement of the quasi-normal modes of a black hole from the ringdown signal of a binary black hole coalescence - is one of the most promising tools to test gravity in the strong-field, large-curvature regime, but without the knowledge of the black hole quasi-normal modes in specific cases of modified gravity theories, only null tests of general relativity are possible. More specifically, we need to know the modes of rotating black holes, because typical compact binary mergers lead to black holes with large spins. In this article we compute, for the first time, the gravitational quasi-normal modes of rotating black holes in a modified gravity theory, up to first order in the spin. We consider Einstein-dilaton Gauss-Bonnet gravity, one of the simplest modifications of general relativity in the large-curvature regime. We find that the shifts in the mode frequencies and damping times due to general relativity modifications are significantly magnified by rotation.