Spinoptics in the presence of axion-like particles in curved spacetime

Abstract

We study the propagation of high-frequency electromagnetic waves coupled to an axionic scalar field in curved spacetime. By applying the effective action approach, we go beyond the standard geometric optics limit and derive spinoptics equations for the axion--Maxwell theory that are valid for arbitrary curved spacetimes and arbitrary axion profiles. These equations allow us to analyze helicity-dependent corrections to photon trajectories arising from the photon's interactions with both the axion field and spacetime curvature. We present representative examples to demonstrate how light trajectories deviate from null geodesics due to spinoptics effects in the presence of an axion field.