Role of spin-curvature and magnetic interactions on circular orbits of particles with magnetic monopole around Bardeen black holes

Abstract

We investigate the dynamics of magnetically charged spinning test particles in the spacetime of the Bardeen regular black hole, sourced by nonlinear electrodynamics and featuring a magnetic monopole charge parameter g. Employing the Mathisson-Papapetrou-Dixon equations supplemented by the Tulczyjew spin condition and extended to include magnetic interactions via the generalized Lorentz force, we derive the effective potential governing the radial motion in the equatorial plane. We analyze the properties of circular orbits, including the location and parameters of the innermost stable circular orbit, and examine how they are modified by the particle's spin s, specific magnetic charge lambda, and the black hole's magnetic charge g. Prograde spin and attractive magnetic interactions reduce the ISCO radius, whereas repulsive interactions and retrograde spin shift it outward. We further impose timelike constraints to exclude unphysical superluminal trajectories, delineating the admissible parameter space. Finally, we explore high-energy particle collisions near the horizon, computing the critical angular momentum and the center-of-mass collision energy. Due to the regular core of the Bardeen spacetime, the Bañados-Silk-West effect is significantly suppressed or capped at finite values, in contrast to singular black hole solutions. These results highlight distinctive phenomenological signatures of regular black holes and offer potential observational probes of nonlinearity in electrodynamics and of magnetic monopoles through accretion processes, extreme-mass-ratio inspirals, and ultra-high-energy particle interactions.