Horizon-brightened acceleration radiation and optical signatures of generic regular black holes from nonlinear electrodynamics

Abstract We investigate horizon-brightened acceleration radiation (HBAR) and optical signatures for a broad class of regular black holes sourced by nonlinear electrodynamics. The spacetimes considered are static, spherically symmetric, and nonsingular, and they include Bardeen-like, and Hayward-like regular black-hole limits as special cases. We characterize the horizon structure and thermodynamic properties, and we compute key optical observables by determining the photon-sphere location and the corresponding shadow size as seen by distant observers, including controlled perturbative limits and full numerical solutions. Using angular-size constraints for Sgr A* and M87* from the Event Horizon Telescope and the GRAVITY collaboration, we perform a Markov Chain Monte Carlo analysis to infer the admissible parameter ranges of the model and to quantify degeneracies among the black-hole mass and nonlinear-electrodynamic parameters. On the quantum side, we develop the near-horizon reduction relevant for HBAR, showing that the dominant sector governing the detector response exhibits conformal behavior and leads to a thermal excitation spectrum governed by the horizon temperature. We formulate a Lindblad master-equation description for the radiation field, identify the thermal steady state, and derive an HBAR entropy–energy relation consistent with a Clausius-type first law. Finally, we establish a Wien-type displacement law for the HBAR spectrum, expressing the peak wavelength in terms of horizon thermodynamic, thereby providing an additional observable link between nonlinear electrodynamics, regularity, and near-horizon quantum radiation.