Charged particle motion around a magnetized Reissner-Nordstr\"{o}m black hole

TL;DR

This paper studies how electric charge and magnetic fields around a magnetized Reissner-Nordström black hole influence test particle orbits, especially the innermost stable circular orbit, and explores energy extraction via particle collisions.

Contribution

It analyzes the combined effects of black hole charge and magnetic field on particle dynamics and ISCO radius, revealing their impact and similarities to Kerr black holes.

Findings

ISCO radius decreases with black hole charge and magnetic field.

Charge effects can dominate over magnetic Lorentz forces.

High magnetic field and charge increase collision energy.

Abstract

We investigate the dynamics of neutral and charged test particles around axially symmetric magnetized black hole spacetime. We consider its electromagnetic field in the black hole vicinity and study its impact on the dynamics of test particles. We determine the radius of the innermost stable circular orbit (ISCO) for neutral and charged test particles and show that the combined effect of black hole electric charge and magnetic field strongly affects the ISCO radius, thus shrinking its values. We also show that the ISCO radius of positively (negatively) charged particle initially gets increased (decreased) and then gets radically altered with an increase in the value of both black hole electric charge and test particle charge. It turns out that the repulsive (attractive) Coulomb force dominates over the Lorentz force arising from the black hole magnetic field. Typically, black hole rotation causes axially symmetric spacetime case. Similarly, it turns out that a magnetized black hole solution also causes axially symmetric spacetime as a consequence of the presence of magnetic field. We study a degeneracy for the value of the ISCO between the Kerr and the magnetized Reissner-Nordstr\"{o}m black hole geometries and show that the combined effects of black hole charge and magnetic field can be mimicked by Kerr spacetime with the spin parameter up to $a/M\approx 0.8$. Finally, we consider the center of mass energy of colliding particles and show that an increase in the values of black hole magnetic field and electric charge leads to high center of mass energy extracted by collision of two particles.