Collisions and circular motion of spinning magnetized particles orbiting magnetized Kerr black holes
Phys. Rev. D 112, 044068 – Published 29 August, 2025
DOI: https://doi.org/10.1103/bl45-hbjm
Abstract
Studying spinning magnetized particles in strong gravitational and electromagnetic fields is crucial for understanding astrophysical processes near black holes, particularly in the scenarios of millisecond pulsars orbiting supermassive or intermediate-mass black holes. In this work, we analyze the circular motion and collisions of such particles in the close environment of a magnetized Kerr black hole, considering both spin-curvature and magnetic dipole interactions. Using the Mathisson-Papapetrou-Dixon (MPD) equations, we derive the effective potential governing the circular motion of spinning magnetized particles and investigate the innermost stable circular orbit (ISCO) under the influence of black hole spin, external magnetic fields, and intrinsic particle spin and magnetic dipole moment. The results reveal how the interaction of the magnetic dipole moment with the external field and spin-curvature interactions significantly alter stable orbits, leading to modifications in accretion dynamics. Furthermore, we explore the center-of-mass energy of such high-energy particle collisions, demonstrating that spin and magnetic interactions can amplify collision energies beyond the standard Bañados-Silk-West (BSW) process, with implications for the production of ultrahigh-energy cosmic rays and the formation of jets in active galactic nuclei and low-luminosity galaxies. Our findings may provide theoretical predictions that can be tested using observations of compact objects in strong magnetic fields, such as pulsars near supermassive black holes.
