Influence of external magnetic fields on charged particle motion around a Schwarzschild-like black hole

TL;DR

This paper explores how external magnetic fields influence particle orbits and collisions near a Schwarzschild-like black hole, revealing potential high-energy phenomena and observable signatures in astrophysical contexts.

Contribution

It demonstrates that magnetic fields significantly alter ISCOs for charged particles and enable unbounded collision energies, offering new insights into black hole magnetospheres.

Findings

Charged particle ISCOs are smaller than neutral ones.

Strong magnetic fields allow ISCOs close to the event horizon.

Collisions can produce unbounded center-of-mass energies.

Abstract

We investigate the dynamics of charged and neutral particles in the vicinity of a Schwarzschild-like black hole immersed in an external magnetic field. We find that the innermost stable circular orbits (ISCOs) for charged particles are systematically smaller than those of neutral particles, demonstrating a fundamental distinction in their orbital dynamics. In the presence of a strong magnetic field, charged particle ISCOs can approach arbitrarily close to the event horizon. We show that collisions between charged particles in ISCOs and neutral particles falling from infinity can produce unbounded center-of-mass energies in the strong-field regime, suggesting the black hole magnetosphere as a natural particle accelerator. Additionally, we apply the relativistic precession model to study quasi-periodic oscillations around the Schwarzschild-like black hole, treating orbital perturbations as coupled harmonic oscillators. Our results provide new insights into high-energy astrophysical processes near magnetized black holes and offer observational signatures through quasi-periodic oscillating frequencies that could be detected by current and future X-ray missions.