Regular Magnetically Charged Black Holes from Nonlinear Electrodynamics: Thermodynamics, Light Deflection, and Orbital Dynamics

TL;DR

This paper explores the thermodynamics, light deflection, and orbital dynamics of regular magnetically charged black holes derived from nonlinear electrodynamics, revealing charge-dependent behaviors and potential observational signatures.

Contribution

It introduces a new class of regular magnetically charged black holes from nonlinear electrodynamics and analyzes their thermodynamics, lensing, and orbital properties with novel charge-dependent effects.

Findings

Extremal magnetic charge exceeds Reissner-Nordström limit.

Charge influences light deflection, causing negative angles at high charges.

Joule-Thomson coefficient indicates cooling for larger charges.

Abstract

We investigate the thermodynamic properties, light deflection, and orbital dynamics of regular magnetically charged black holes (NRCBHs) arising from nonlinear electrodynamics (NED) coupled to general relativity. The metric function $f(r)$ ensures complete regularity at the origin while maintaining asymptotic flatness, with the extremal magnetic charge limit reaching $q_{\text{ext}} \approx 2.54M$, significantly exceeding the Reissner-Nordstr\"{o}m value. Using the quantum tunneling framework, we derive the Hawking temperature and incorporate generalized uncertainty principle (GUP) corrections, showing $T_{\text{GUP}} = (f'(r_h)/4\pi)\sqrt{1-2\beta m_p^2}$. The weak deflection of light is analyzed through the Gauss-Bonnet theorem (GBT), revealing charge-dependent behavior where large $q$ values lead to negative deflection angles due to electromagnetic repulsion. Plasma effects further modify the deflection through the refractive index $n(r) = \sqrt{1 - \omega_p^2(r)f(r)/\omega_0^2}$. Keplerian motion analysis demonstrates that the angular velocity $\Omega(r)$ exhibits charge-sensitive maxima related to quasi-periodic oscillations (QPOs) in accretion disks. Finally, we examine Joule-Thomson expansion (JTE) properties, finding that the coefficient $\mu_J$ indicates cooling behavior for higher charges and larger event horizons. Our results provide comprehensive insights into the observational signatures of NRCBHs, with implications for gravitational lensing, X-ray astronomy, and tests of nonlinear electromagnetic theories in strong gravitational fields.