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arXiv · 2605.25094

Chaotic motion of particles around a Schwarzschild black hole in a swirling electromagnetic background

Wenbin Li·Yu-Qi Lei·Xian-Hui Ge
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Abstract

We investigate the particle motion around a Schwarzschild black hole immersed in a swirling Bertotti-Robinson-Bonnor-Melvin background. This spacetime provides a physically well-motivated framework for studying how the two different electromagnetic components and the swirling deformation affect particle dynamics near compact objects. By employing Poincar\'{e} sections, the maximum Lyapunov exponent, the Fast Lyapunov indicator, recurrence analysis and bifurcation diagrams, we show that chaotic motion can already appear in the non-swirling Schwarzschild-Bertotti-Robinson black hole. This indicates that the swirling background is not a necessary condition for chaos in this family of spacetimes, it mainly shifts the parameter region where chaos occurs. We further find that the effects of the two electromagnetic fields are very complicated. In particular, the existence of bound orbits is strongly restricted by the strengths of the two electromagnetic fields and their relative direction. These results provide rich numerical evidence that the chaotic motion of particles is associated with the nonlinear interaction between the accessible phase space, the electromagnetic backreaction and the swirling deformation.

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Wenbin Li, Yu-Qi Lei, Xian-Hui Ge. 2026-05-24. Chaotic motion of particles around a Schwarzschild black hole in a swirling electromagnetic background. https://arxiv.org/abs/2605.25094

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