Spinning black holes in Einstein--Gauss-Bonnet--dilaton theory: non-perturbative solutions

TL;DR

This paper explores non-perturbative spinning black hole solutions in Einstein--Gauss-Bonnet--dilaton theory, revealing unique properties such as scalar fields outside horizons and bounds on mass and angular momentum, differing from Kerr black holes.

Contribution

It provides the first non-perturbative solutions for spinning black holes in EGBd theory, detailing their properties and parameter space.

Findings

EGBd black holes have a lower mass bound.

Their angular momentum can surpass Kerr limits.

Extremal solutions are singular with diverging scalar fields.

Abstract

We present an investigation of spinning black holes in Einstein--Gauss-Bonnet--dilaton (EGBd) theory. The solutions are found within a non-perturbative approach, by directly solving the field equations. These stationary axially symmetric black holes are asymptotically flat. They possess a non-trivial scalar field outside their regular event horizon. We present an overview of the parameter space of the solutions together with a study of their basic properties. We point out that the EGBd black holes can exhibit some physical differences when compared to the Kerr solution. For example, their mass is always bounded from below, while their angular momentum can exceed the Kerr bound, Also, in contrast to the Kerr case, the extremal solutions are singular, with the scalar field diverging on the horizon.