Stable Bound Orbits of Massless Particles around a Black Ring

TL;DR

This paper demonstrates the existence of stable bound orbits of massless particles around a black ring, revealing new dynamical features of black ring spacetimes and expanding understanding of black hole physics.

Contribution

It provides the first example of stable bound orbits of massless particles around a black object, specifically in black ring spacetimes, highlighting novel gravitational phenomena.

Findings

Stable stationary orbits of massless particles in black rings

Existence of nonstationary massless particles bounded outside the horizon

Stable bound orbits occur when the black ring's thickness parameter is below a critical value

Abstract

We study the geodesic motion of massless particles in singly rotating black ring spacetimes. We find stable stationary orbits of massless particles in toroidal spiral shape in the case that the thickness parameter of a black ring is less than a critical value. Furthermore, there exist nonstationary massless particles bounded in a finite region outside the horizon. This is the first example of stable bound orbits of massless particles around a black object.