Perturbed black holes in Einstein-dilaton-Gauss-Bonnet gravity: Stability, ringdown, and gravitational-wave emission

TL;DR

This paper investigates the stability, quasinormal modes, and gravitational-wave signals of black holes in Einstein-dilaton-Gauss-Bonnet gravity, suggesting future observations could test deviations from general relativity.

Contribution

It provides the first comprehensive analysis of black hole stability and gravitational-wave signatures in Einstein-dilaton-Gauss-Bonnet gravity, highlighting potential observational tests.

Findings

Black holes are linearly stable against perturbations in this theory.

Quasinormal modes can be excited during black hole collisions.

Future gravitational-wave detections could constrain the theory's coupling parameter.

Abstract

Gravitational waves emitted by distorted black holes---such as those arising from the coalescence of two neutron stars or black holes---carry not only information about the corresponding spacetime but also about the underlying theory of gravity. Although general relativity remains the simplest, most elegant and viable theory of gravitation, there are generic and robust arguments indicating that it is not the ultimate description of the gravitational universe. Here we focus on a particularly appealing extension of general relativity, which corrects Einstein's theory through the addition of terms which are second order in curvature: the topological Gauss-Bonnet invariant coupled to a dilaton. We study gravitational-wave emission from black holes in this theory, and {\bf(i)} find strong evidence that black holes are linearly (mode) stable against both axial and polar perturbations; {\bf(ii)} discuss how the quasinormal modes of black holes can be excited during collisions involving black holes, and finally {\bf(iii)} show that future ringdown detections with large signal-to-noise ratio would improve current constraints on the coupling parameter of the theory.