Accretion Disk Around Charged Black Holes with Nonlinear Electrodynamics
Yusupova R.M., Karimov R.Kh., Izmailov R.N.

Received: May 4, 2026

DOI: 10.31857/S0044451026120033

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We investigate a geometrically thin, optically thick accretion disk around a charged regular Balart-Vagenas black hole and compare its kinematic and radiative properties with those of the Reissner-Nordström, Schwarzschild, and tidal charged black holes. Restricting the parameter to a=1, which provides the charge correction in the asymptotic expansion, we examine two values of the parameter γ , namely γ =1/2 and γ =1/6. We compute the horizon radius, the marginally stable orbit, the flux, the temperature distribution, the spectral luminosity, and the accretion efficiency for a stellar-mass compact object with M = 15 M_\odot and \dot M₀ = 10¹⁹ g/s. For both values of γ , increasing the charge shifts the marginally stable orbit inward and increases the accretion efficiency. The influence of the parameter γ on the radiative properties of the disk is also demonstrated. At γ =1/2, the Balart-Vagenas black hole yields substantially larger flux, temperature, and spectral maxima than in the Reissner-Nordström and Schwarzschild cases, whereas for γ =1/6 it remains close (but not identical) to the Reissner-Nordström solution. For a more accurate analysis, we also normalize the metric charge by the asymptotic charge Q_as² = 6γ q². For a=1, the Balart-Vagenas metric and all thin accretion disk observables depend on γ and q only through Q_as, and consequently the results for γ =1/6 and γ =1/2 coincide exactly at fixed Q_as/M. At Q_as/M = 0.5, the flux, temperature, and spectral maxima of the Balart-Vagenas black hole are lower than the corresponding Reissner-Nordström black hole values by approximately 0.61%, 0.15%, and 0.19%, respectively. Therefore, the large enhancement found at fixed q/M is primarily associated with the different charge normalization and proximity to extremality, whereas the residual nonlinear electrodynamic correction at fixed asymptotic charge is small. In the case of tidal charge, the accretion parameters of the charged black hole turn out to be lower than in the classical cases. Thus, depending on the parameters of nonlinear electrodynamics in the Balart-Vagenas solution, the accretion characteristics can either mimic the classical charged solution or lead to significantly more intense radiation. Keywords: regular black holes, nonlinear electrodynamics, Balart-Vagenas metric, thin accretion disk, Novikov-Thorne model, accretion efficiency