Self-force and motion of stars around black holes

TL;DR

This paper discusses the theoretical modeling of star motion around black holes, focusing on self-force effects and perturbation methods relevant for gravitational wave detection.

Contribution

It introduces advanced techniques for calculating the self-force on stars near black holes, including regularization methods and non-adiabatic trajectory analysis.

Findings

Development of regularization techniques for self-force calculations

Application of tail and Green function methods to star motion

Insights into non-adiabatic orbital evolution near black holes

Abstract

Through detection by low gravitational wave space interferometers, the capture of stars by supermassive black holes will constitute a giant step forward in the understanding of gravitation in strong field. The impact of the perturbations on the motion of the star is computed via the tail, the back-scattered part of the perturbations, or via a radiative Green function. In the former approach, the self-force acts upon the background geodesic, while in the latter, the geodesic is conceived in the total (background plus perturbations) field. Regularisations (mode-sum and Riemann-Hurwitz $\zeta$ function) intervene to cancel divergencies coming from the infinitesimal size of the particle. The non-adiabatic trajectories require the most sophisticated techniques for studying the evolution of the motion, like the self-consistent approach.