Self force on particle in orbit around a black hole

TL;DR

This paper calculates the self force on a scalar charge in circular orbit around a Schwarzschild black hole, providing detailed results across various radii and velocities, especially near the black hole where relativistic effects are significant.

Contribution

It introduces a direct mode decomposition and regularization method to compute the self force at arbitrary radii and velocities, including non-geodesic orbits, around a black hole.

Findings

Radial self force can be repulsive or attractive depending on orbit

Self force computed for both geodesic and non-geodesic orbits

Results applicable near the black hole where relativistic effects dominate

Abstract

We study the self force acting on a scalar charge in uniform circular motion around a Schwarzschild black hole. The analysis is based on a direct calculation of the self force via mode decomposition, and on a regularization procedure based on Ori's mode-sum regularization prescription. We find the four self-force at arbitrary radii and angular velocities (both geodesic and non-geodesic), in particular near the black hole, where general-relativistic effects are strongest, and for fast motion. We find the radial component of the self force to be repulsive or attractive, depending on the orbit.