Ring singularity

Routing (electronic design automation)

Quantum mechanics

Schwarzschild radius

Charged black hole

Spacetime

Mathematical physics

Kerr metric

Hypersurface

Rotating black hole

Null (SQL)

Singularity

Event horizon

Scalar field

Computer science

Classical mechanics

Computer network

Routing protocol

Physics

Penrose process

Database

Scalar (mathematics)

Mathematics

Angular momentum

Link-state routing protocol

Mathematical analysis

Geometry

Naked singularity

Black hole (networking)

Killing vector field

Journal of High Energy Physics

Starting from a recently constructed stealth Kerr solution of higher order scalar tensor theory involving scalar hair, we analytically construct disformal versions of the Kerr spacetime with a constant degree of disformality and a regular scalar field. While the disformed metric has only a ring singularity and asymptotically is quite similar to Kerr, it is found to be neither Ricci flat nor circular. Non-circularity has far reaching consequences on the structure of the solution. As we approach the rotating compact object from asymptotic infinity we find a static limit ergosurface similar to the Kerr spacetime with an enclosed ergoregion. However, the stationary limit of infalling observers is found to be a timelike hypersurface. A candidate event horizon is found in the interior of this stationary limit surface. It is a null hypersurface generated by a null congruence of light rays which are no longer Killing vectors. Under a mild regularity assumption, we find that the candidate surface is indeed an event horizon and the disformed Kerr metric is therefore a black hole quite distinct from the Kerr solution.

Disforming the Kerr metric