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arXiv · 2603.17728

Electromagnetic radiation-reaction near black holes: orbital widening and the role of the tail

Bakhtinur Juraev·Arman Tursunov·Zdeněk Stuchlík·Martin Kološ·Dmitri V. Gal'tsov
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Abstract

We investigate the orbital evolution of a classical charged particle around a Schwarzschild black hole immersed in an external, uniform magnetic field, taking into full account both local radiation-reaction and the nonlocal tail self-force arising in curved spacetime. Starting from the DeWitt-Brehme equation and its Landau-Lifshitz reduction, we derive analytic expressions for the conservative and dissipative components of the electromagnetic self-force in both the weak-field (Newtonian) and strong-field regimes. By implementing backward-in-time integration of the third-order DeWitt-Brehme equation alongside the second-order Landau-Lifshitz equation, we demonstrate that the so-called orbital widening effect persists even when the tail term is included, and that for astrophysically realistic charge-to-mass ratios the tail contribution to the trajectory is negligible. We further show that this widening is directly controlled by the product of the magnetic field and radiation-reaction parameters and can be captured in the Newtonian limit. Finally, we identify a scaling symmetry showing that simulations with moderate parameter values can accurately represent the dynamics in realistic astrophysical conditions, confirming that orbital widening is a robust phenomenon that can persist even in astrophysical black hole environments.

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Bakhtinur Juraev, Arman Tursunov, Zdeněk Stuchlík, Martin Kološ, Dmitri V. Gal'tsov. 2026-03-18. Electromagnetic radiation-reaction near black holes: orbital widening and the role of the tail. https://arxiv.org/abs/2603.17728

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