Chaos of charged particles in quadrupole magnetic fields under Schwarzschild backgrounds

Fuente: arXiv
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Auteurs principaux: Zhang, Qihan, Wu, Xin
Format: Preprint
Publié: 2025
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author Zhang, Qihan
Wu, Xin
author_facet Zhang, Qihan
Wu, Xin
contents A four-vector potential of an external test electromagnetic field in a Schwarzschild background is described in terms of a combination of dipole and quadrupole magnetic fields. This combination is an interior solution of the source-free Maxwell equations. Such external test magnetic fields cause the dynamics of charged particles around the black hole to be nonintegrable, and are mainly responsible for chaotic dynamics of charged particles. In addition to the external magnetic fields, some circumstances should be required for the onset of chaos. The effect of the magnetic fields on chaos is shown clearly through an explicit symplectic integrator and a fast Lyapunov indicator. The inclusion of the quadrupole magnetic fields easily induces chaos, compared with that of the dipole magnetic fields. This result is because the Lorentz forces from the quadrupole magnetic fields are larger than those from the dipole magnetic fields. In addition, the Lorentz forces act as attractive forces, which are helpful to bring the occurrence of chaos in the nonintegrable case.
format Preprint
id arxiv_https___arxiv_org_abs_2507_12752
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Chaos of charged particles in quadrupole magnetic fields under Schwarzschild backgrounds
Zhang, Qihan
Wu, Xin
General Relativity and Quantum Cosmology
Astrophysics of Galaxies
A four-vector potential of an external test electromagnetic field in a Schwarzschild background is described in terms of a combination of dipole and quadrupole magnetic fields. This combination is an interior solution of the source-free Maxwell equations. Such external test magnetic fields cause the dynamics of charged particles around the black hole to be nonintegrable, and are mainly responsible for chaotic dynamics of charged particles. In addition to the external magnetic fields, some circumstances should be required for the onset of chaos. The effect of the magnetic fields on chaos is shown clearly through an explicit symplectic integrator and a fast Lyapunov indicator. The inclusion of the quadrupole magnetic fields easily induces chaos, compared with that of the dipole magnetic fields. This result is because the Lorentz forces from the quadrupole magnetic fields are larger than those from the dipole magnetic fields. In addition, the Lorentz forces act as attractive forces, which are helpful to bring the occurrence of chaos in the nonintegrable case.
title Chaos of charged particles in quadrupole magnetic fields under Schwarzschild backgrounds
topic General Relativity and Quantum Cosmology
Astrophysics of Galaxies
url https://arxiv.org/abs/2507.12752