Bounds on the minimum orbital periods of non-singular Hayward and Bardeen black holes

TL;DR

This paper investigates the minimum orbital periods around non-singular Hayward and Bardeen black holes, confirming they adhere to previously conjectured universal bounds, suggesting these bounds relate to horizons rather than singularities.

Contribution

It demonstrates that non-singular Hayward and Bardeen black holes satisfy the universal bounds on minimum orbital periods through analytical and numerical analysis.

Findings

Both black holes conform to the bounds $4 ext{ extpi} M \,\leqslant\, T_{min} \,\leqslant\, 6\sqrt{3}\text{ extpi} M$

Bounds are likely linked to the horizon presence, not the singularity

Results support the universality of orbital period bounds for various black hole types

Abstract

Based on previous studies, universal bounds $4\pi M \leqslant T_{min} \leqslant 6\sqrt{3}\pi M$ were conjectured to be characteristic properties of black hole spacetimes, where $M$ represents the mass of black holes and $T_{min}$ is the minimum orbital periods around black holes. In this work, we explore the minimum orbital periods of objects around Hayward and Bardeen black holes without central singularities. By combining analytical and numerical methods, we show that both Hayward and Bardeen black holes conform to these bounds. Our results imply that such bounds may be connected to the presence of the black hole horizon rather than the singularity.