Testing the Kerr black hole hypothesis

TL;DR

This paper reviews current efforts and recent progress in testing whether astrophysical black hole candidates are accurately described by the Kerr metric, aiming to confirm their nature as true Kerr black holes.

Contribution

It provides a concise overview of the latest developments and ongoing research in observationally testing the Kerr black hole hypothesis.

Findings

Growing observational evidence supports Kerr black hole models

Recent experiments are increasingly capable of testing deviations from Kerr geometry

Progress in theoretical and observational techniques enhances black hole hypothesis testing

Abstract

It is thought that the final product of the gravitational collapse is a Kerr black hole and astronomers have discovered several good astrophysical candidates. While there is some indirect evidence suggesting that the latter have an event horizon, and therefore that they are black holes, a proof that the space-time around these objects is described by the Kerr geometry is still lacking. Recently, there has been an increasing interest in the possibility of testing the Kerr black hole hypothesis with present and future experiments. In this paper, I briefly review the state of the art of the field, focussing on some recent results and work in progress.