Highly relativistic circular orbits of spinning particle in the Kerr field

TL;DR

This paper investigates highly relativistic circular orbits of spinning particles in Kerr spacetime, revealing that spin significantly extends the region of possible orbits and influences their stability through spin-gravity coupling.

Contribution

It provides a detailed analysis of spinning particle orbits in Kerr spacetime, highlighting the wider existence region and the effects of spin-gravity interactions compared to spinless particles.

Findings

Spinning particles have a broader range of circular orbits than spinless particles.

Spin-gravity coupling can cause both attractive and repulsive effects on particle orbits.

Numerical estimates for electrons, protons, and neutrinos in black hole fields are provided.

Abstract

The Mathisson-Papapetrou equations in Kerr's background are considered. The region of existence of highly relativistic planar circular orbits of a spinning particle in this background and dependence of the particle's Lorentz $\gamma$-factor on its spin and radial coordinate are investigated. It is shown that in contrast to the highly relativistic circular orbits of a spinless particle the corresponding orbits of a spinning particle are allowed in much wider space region. Some of these orbits show the significant attractive action of the spin-gravity coupling on a particle and others are caused by the significant repulsive action. Numerical estimates for electrons, protons and neutrinos in the gravitational field of black holes are presented.