Strong deflection of massive particles in spherically symmetric spacetimes
Abstract
Near a gravitating compact object, massive particles traveling along timelike geodesics are gravitationally deflected similarly to light. In this paper, we study the deflection angles of these particles in the strong deflection limit. This analytical approximation applies when particles in unbound orbits approach the compact object very closely, circle around it at a radius close to that of the unstable circular orbit, and eventually escape. While previous studies have provided results for particular metrics, we offer a general solution applicable to any static, spherically symmetric and asymptotically flat spacetime. After briefly reviewing the exact expression for the deflection angle of massive particles, we present a strong deflection limit analysis for this general case. The developed formulas are then applied to three particular metrics: Schwarzschild, Reissner-Nordstr\"om and Janis-Newman-Winicour.
Keywords
Cite
@article{arxiv.2412.16712,
title = {Strong deflection of massive particles in spherically symmetric spacetimes},
author = {Fabiano Feleppa and Valerio Bozza and Oleg Yu. Tsupko},
journal= {arXiv preprint arXiv:2412.16712},
year = {2026}
}
Comments
16 pages, 11 figures; v2: typos corrected, version accepted for publication in Physical Review D; v3: published version; v4: further typos fixed; v5: minor edits for clarity; v6: corrected typos in Eqs. (23), (24), (43), and (58); no change to the conclusions