Acceleration radiation from derivative-coupled atoms falling in modified gravity black holes

Abstract

The interaction of quantum detector models with fields in curved spacetimes provides fundamental insights into phenomena such as Hawking and Unruh radiation. While standard models typically assume a minimal coupling between the detector and the field, physically motivated derivative couplings, which are sensitive to field gradients, have been less explored, particularly in the context of modified gravity theories. In this paper, we develop a general framework to analyze the acceleration radiation from a two-level atomic detector with a derivative coupling undergoing a radial geodesic infall into a generic static, spherically symmetric black hole. We derive a general integral expression for the excitation probability and apply it to two distinct spacetimes. For an extended uncertainty principle (EUP) black hole, we demonstrate that the detector radiates with a perfect thermal spectrum at the precise Hawking temperature, reinforcing the universality of this phenomenon. For a black hole solution in a Ricci-coupled Bumblebee gravity model, the radiation is also thermal. Still, its temperature is modified in direct correspondence with the theory's Lorentz-violating parameters, consistent with the modified Hawking temperature. Furthermore, we demonstrate that derivative coupling results in a significantly enhanced entropy flux compared to minimal coupling models. Our results establish acceleration radiation as a sensitive probe of near-horizon physics and demonstrate that this phenomenon can provide distinct observational signatures to test General Relativity (GR) and alternative theories of gravity in the strong-field regime.