Electromagnetic self-force on a charged particle on Kerr spacetime: equatorial circular orbits

TL;DR

This paper computes the electromagnetic self-force on a charged particle in equatorial circular orbits around a Kerr black hole, confirming energy balance with radiated flux and analyzing the conservative force component.

Contribution

It provides the first detailed calculation of the electromagnetic self-force on a charged particle in Kerr spacetime, including both dissipative and conservative parts, with numerical and post-Newtonian analysis.

Findings

Dissipative self-force balances radiated flux at infinity and horizon.

Prograde orbits can induce superradiance but cannot produce floating orbits.

Electromagnetic and gravitational self-forces are compared for innermost stable circular orbits.

Abstract

We calculate the self-force acting on a charged particle on a circular geodesic orbit in the equatorial plane of a rotating black hole. We show by direct calculation that the dissipative self-force balances with the sum of the flux radiated to infinity and through the black hole horizon. Prograde orbits are found to stimulate black hole superradiance, but we confirm that the condition for floating orbits cannot be met. We calculate the conservative component of the self-force by application of the mode sum regularization method, and we present a selection of numerical results. By numerical fitting, we extract the leading-order coefficients in post-Newtonian expansions. The self-force on the innermost stable circular orbits of the Kerr spacetime is calculated, and comparisons are drawn between the electromagnetic and gravitational self forces.