Magnetic-field-induced chaos of charged particles around a rotating black hole in a King-type dark matter halo
Abstract
We investigate the dynamics of charged test particles around a rotating black hole embedded in a King-type dark matter halo and subjected to a prescribed, asymptotically uniform magnetic field. We adopt an effective rotating geometry constructed from a static halo seed through a modified Newman--Janis prescription and a test electromagnetic field that generally requires supporting currents in the nonvacuum background. In the absence of magnetic coupling, the timelike Hamilton--Jacobi equation separates and admits a Carter-type constant, providing an integrable reference system. We characterize the orbital dynamics using Poincaré sections and tangent-vector growth diagnostics, including fast Lyapunov indicators and finite-time Lyapunov exponents, with mass-shell monitoring and numerical refinement checks. For the sampled initial conditions, increasing the magnetic coupling can produce a transition from regular motion to scattered Poincaré sections with sustained positive finite-time growth rates. At fixed magnetic coupling, the two higher-density halo cases yield larger finite-time exponents for a representative chaotic orbit family, whereas the weak-halo correction is not resolved consistently under numerical refinement. A different initial condition yields a closed Poincaré curve and a decreasing finite-time exponent over an extended integration, supporting regular motion despite the nonzero magnetic coupling. These results show that the King-type halo modulates magnetic-field-induced orbital instability in an initial-condition-dependent manner, while regular motion persists within the magnetized system.
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BibTeX
@misc{wang2026magneticfieldinduced,
title = {{Magnetic-field-induced chaos of charged particles around a rotating black hole in a King-type dark matter halo}},
author = {Yu Wang and Meilin Liu and Haiguang Xu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.04521},
eprint = {2610.04521},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.04521},
}
RIS
TY - UNPB
TI - Magnetic-field-induced chaos of charged particles around a rotating black hole in a King-type dark matter halo
AU - Yu Wang
AU - Meilin Liu
AU - Haiguang Xu
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2610.04521
UR - https://arxiv.org/abs/2610.04521
AB - We investigate the dynamics of charged test particles around a rotating black hole embedded in a King-type dark matter halo and subjected to a prescribed, asymptotically uniform magnetic field. We adopt an effective rotating geometry constructed from a static halo seed through a modified Newman--Janis prescription and a test electromagnetic field that generally requires supporting currents in the nonvacuum background. In the absence of magnetic coupling, the timelike Hamilton--Jacobi equation separates and admits a Carter-type constant, providing an integrable reference system. We characterize the orbital dynamics using Poincaré sections and tangent-vector growth diagnostics, including fast Lyapunov indicators and finite-time Lyapunov exponents, with mass-shell monitoring and numerical refinement checks. For the sampled initial conditions, increasing the magnetic coupling can produce a transition from regular motion to scattered Poincaré sections with sustained positive finite-time growth rates. At fixed magnetic coupling, the two higher-density halo cases yield larger finite-time exponents for a representative chaotic orbit family, whereas the weak-halo correction is not resolved consistently under numerical refinement. A different initial condition yields a closed Poincaré curve and a decreasing finite-time exponent over an extended integration, supporting regular motion despite the nonzero magnetic coupling. These results show that the King-type halo modulates magnetic-field-induced orbital instability in an initial-condition-dependent manner, while regular motion persists within the magnetized system.
ER -