Innermost stable circular orbit of spinning particle in charged spinning black hole background

TL;DR

This paper studies the innermost stable circular orbit (ISCO) of a spinning test particle around Kerr-Newman black holes, revealing how spin affects orbit stability and radius, with implications for black hole physics.

Contribution

It introduces a superluminal constraint to determine the ISCO for spinning particles in charged rotating black hole backgrounds, providing new numerical relations.

Findings

ISCO radius decreases with particle spin

Spinning particles can have superluminal motion if spin is too large

Relations between ISCO, black hole, and particle properties are numerically obtained

Abstract

In this paper we investigate the innermost stable circular orbit (ISCO) for a classical spinning test particle in the background of Kerr-Newman black hole. It is shown that the orbit of the spinning particle is related to the spin of the test particle. The motion of the spinning test particle will be superluminal if its spin is too large. We give an additional condition by considering the superluminal constraint for the ISCO in the black hole backgrounds. We obtain numerically the relations between the ISCO and the properties of the black holes and the test particle. It is found that the radius of the ISCO for a spinning test particle is smaller than that of a non-spinning test particle in the black hole backgrounds.