Black holes in Einstein-Gau\ss -Bonnet-dilaton theory

TL;DR

This paper explores black holes within Einstein-Gauss-Bonnet-dilaton theory, revealing deviations from classical Kerr black holes in their properties and stability, with implications for gravitational wave observations.

Contribution

It introduces generalized black hole solutions in Einstein-Gauss-Bonnet-dilaton theory and analyzes their stability and observational signatures.

Findings

Black holes can slightly exceed Kerr spin bound.

Significant deviations in innermost stable orbit properties.

Static black holes are mode stable against perturbations.

Abstract

Generalizations of the Schwarzschild and Kerr black holes are discussed in an astrophysically viable generalized theory of gravity, which includes higher curvature corrections in the form of the Gauss-Bonnet term, coupled to a dilaton. The angular momentum of these black holes can slightly exceed the Kerr bound. The location and the orbital frequency of particles in their innermost stable circular orbits can deviate significantly from the respective Kerr values. Study of the quasinormal modes of the static black holes gives strong evidence that they are mode stable against polar and axial perturbations. Future gravitational wave observations should improve the current bound on the Gauss-Bonnet coupling constant, based on observations of the low-mass x-ray binary A 0620-00.