Bound orbits around charged black holes with exponential and logarithmic electrodynamics (2104.12071v5)

Abstract: We present exact black hole solutions endowed with magnetic charge coming from exponential and logarithmic nonlinear electrodynamics (NLED). Classically, we analyze the null and timelike geodesics, all of which contain both the bound and the scattering orbits. Using the effective geometry formalism, we found that photon can have nontrivial stable (both circular and non-circular) bound orbits. The noncircular bound orbits for the one-horizon case mostly take the form of precessed ellipse. For the extremal and three-horizon cases we find many-world orbits where photon crosses the outer horizon but bounces back without hitting the true (or second, respectively) horizon, producing the epicycloid and epitrochoid paths. Semiclassically, we investigate their Hawking temperature, stability, and phase transition. The nonlinearity enables black hole stability with smaller radius than its RN counterpart. However, for very-strong nonlinear regime, the thermodynamic behavior tends to be Schwarzschild-like.