QPO-Based Bayesian Constraints on Charged Particle Dynamics Around Magnetized Schwarzschild Black Holes

Abstract: We study the motion of charged particles with a magnetic dipole moment orbiting a Schwarzschild black hole immersed in an external paraboloidal magnetic field. The interaction between the particle's intrinsic magnetic moment and the black hole magnetosphere is modeled through a dipole coupling, and the equations of motion are derived using the Hamilton-Jacobi formalism. We analyze equatorial circular orbits, the innermost stable circular orbit, and epicyclic oscillations, showing that the magnetic field strength and coupling parameter produce competing effects on orbital stability and fundamental frequencies. These frequencies are applied to model high-frequency quasi-periodic oscillations within the relativistic precession framework. Using observational QPO data from stellar-mass, intermediate-mass, and supermassive black holes, we perform a Bayesian parameter estimation based on Markov Chain Monte Carlo techniques. The analysis constrains the black hole mass, magnetic field strength, field geometry, coupling parameter, and QPO orbital radius, highlighting the role of magnetospheric interactions in shaping both particle dynamics and timing properties of accreting black holes.