Violation of the Carter-Israel conjecture and its astrophysical implications

TL;DR

This paper explores the potential astrophysical consequences of objects violating the Kerr bound, challenging the Carter-Israel conjecture and offering a way to test the nature of massive compact objects in the universe.

Contribution

It proposes that observing violations of the Kerr bound can serve as a test for the Carter-Israel conjecture and the true nature of astrophysical compact objects.

Findings

Violations of the Kerr bound could indicate non-Kerr black holes or exotic compact objects.

Astrophysical implications include potential observable signatures of such violations.

The paper discusses how these violations can be used to test fundamental conjectures in black hole physics.

Abstract

On the basis of the Carter-Israel conjecture, today we believe that some compact and massive objects in the Galaxy and in the Universe are Kerr black holes. However, this idea cannot yet be confirmed by observations. We can currently obtain reliable estimates of the masses of these objects, but we do not know if the space-time around them is described by the Kerr metric and if they have an event horizon. A fundamental limit for a Kerr black hole is the Kerr bound $|a_*| \le 1$. Here I discuss some astrophysical implications associated with the violation of this bound, which can thus be used to test the Carter-Israel conjecture.