The general relativistic Poynting-Robertson effect. II: A photon flux with nonzero angular momentum

TL;DR

This paper investigates how a test particle moves under the influence of a photon flux with nonzero angular momentum in a relativistic spacetime, revealing multiple equilibrium orbits when photon angular momentum is high.

Contribution

It extends previous models by analyzing the particle motion with photon fluxes carrying arbitrary angular momentum in Kerr and Schwarzschild spacetimes.

Findings

Multiple equilibrium circular orbits occur with high photon angular momentum.

A unique equilibrium orbit exists for zero photon angular momentum.

The study generalizes previous results limited to zero angular momentum flux.

Abstract

We study the motion of a test particle in a stationary, axially and reflection symmetric spacetime of a central compact object, as affected by interaction with a test radiation field of the same symmetries. Considering the radiation flux with fixed but arbitrary (non-zero) angular momentum, we extend previous results limited to an equatorial motion within a zero-angular-momentum photon flux in the Kerr and Schwarzschild backgrounds. While a unique equilibrium circular orbit exists if the photon flux has zero angular momentum, multiple such orbits appear if the photon angular momentum is sufficiently high.