Non-Linear Effects in Non-Kerr spacetimes

TL;DR

This paper explores how deviations from the Kerr metric in non-Kerr spacetimes, such as Manko-Novikov, can be detected through their unique non-integrable features in extreme mass ratio inspirals.

Contribution

It introduces a method to identify non-Kerr spacetimes by analyzing the non-integrable dynamics of EMRIs in bumpy black hole models.

Findings

Non-Kerr spacetimes lack certain symmetries, leading to non-integrable geodesic motion.

EMRIs in these spacetimes exhibit distinctive dynamical features.

Detectability of deviations depends on the non-integrability signatures.

Abstract

There is a chance that the spacetime around massive compact objects which are expected to be black holes is not described by the Kerr metric, but by a metric which can be considered as a perturbation of the Kerr metric. These non-Kerr spacetimes are also known as bumpy black hole spacetimes. We expect that, if some kind of a bumpy black hole exists, the spacetime around it should possess some features which will make the divergence from a Kerr spacetime detectable. One of the differences is that these non-Kerr spacetimes do not posses all the symmetries needed to make them integrable. We discuss how we can take advantage of this fact by examining EMRIs into the Manko-Novikov spacetime.