Hyperbolic scattering of spinning particles by a Kerr black hole

TL;DR

This paper analytically studies how the spin of a test particle affects its scattering behavior around a Kerr black hole, extending previous non-rotating results to include linear spin effects.

Contribution

It provides the first analytical calculation of spin-induced modifications to scattering angles and capture conditions for spinning particles in Kerr spacetime.

Findings

Spin alters the scattering angle and periastron shift.

Derived conditions for particle capture based on spin effects.

Extended analysis to include potential spin-squared corrections.

Abstract

We investigate the scattering of a spinning test particle by a Kerr black hole within the Mathisson-Papapetrou-Dixon model to linear order in spin. The particle's spin and orbital angular momentum are taken to be aligned with the black hole's spin. Both the particle's mass and spin length are assumed to be small in comparison with the characteristic length scale of the background curvature, in order to avoid backreaction effects. We analytically compute the modifications due to the particle's spin to the scattering angle, the periastron shift, and the condition for capture by the black hole, extending previous results valid for the nonrotating Schwarzschild background. Finally, we discuss how to generalize the present analysis beyond the linear approximation in spin, including spin-squared corrections in the case of a black-hole-like quadrupolar structure for the extended test body.