Horizon-Brightened Acceleration Radiation and the Deflection Angle Near a Degenerate Photon Sphere of Schwarzschild-like Quantum-Corrected Black Hole

Abstract

We investigate horizon-brightened acceleration radiation (HBAR) and a strong-deflection expansion for the deflection angle of light rays scattered in the vicinity of a degenerate photon sphere, within the context of a quantum-corrected black hole spacetime. We characterize the horizon structure and thermodynamics, and we extract the divergent part of the deflection-angle integral from the near-marginal-orbit contribution using a nonsingular prescription at marginality, obtaining a unique leading power-law term. In terms of the closest-approach radius, the strong-deflection leading coefficient factorizes into a universal branch constant and a local factor involving the third derivative of the effective potential at the degenerate photon sphere. On the quantum side, we develop the near-horizon reduction relevant to HBAR, demonstrating that the dominant sector governing the detector response exhibits conformal behavior and yields a thermal excitation spectrum characterized by the horizon temperature. We adopt a Lindblad master-equation framework for the radiation field, establish the existence of a thermal steady state, and obtain an HBAR entropy-energy relation that satisfies a Clausius-type first-law structure. Also, we derive a Wien-type displacement law for the HBAR spectrum, connecting the peak wavelength to horizon thermodynamics and thereby providing an additional observable probe of quantum gravity via near-horizon radiation.