Light Deflection due to Spinoptic Effects in Parametrized and Spherically Symmetric Hairy Black Holes

TL;DR

This paper investigates how light's helicity interacts with spacetime curvature to cause angular deflections in black hole backgrounds, using spinoptics formalism in parametrized and hairy black hole models.

Contribution

It introduces a detailed analysis of helicity-dependent light deflection in spherically symmetric black holes using spinoptics, highlighting effects of parametrization and hair parameters.

Findings

Helicity-curvature interaction causes significant out-of-plane light deflection.

Deflection angles depend on RZ parametrization coefficients and hairy black hole parameters.

RZ parametrization can approximate hairy black holes with limitations.

Abstract

In the standard geometric optics approximation, null rays propagating in a spherically symmetric black hole background follow planar geodesics. This picture changes, however, when the helicity-dependent effects of light are incorporated into the dynamics. Specifically, the interaction between the helicity of light and the spacetime curvature induces a significant angular deflection out of the geodesic plane. In this paper, we employ the spinoptics formalism to study light deflection due to the helicity-curvature interaction in two spherically symmetric geometries: the Rezzolla--Zhidenko (RZ) parametrized metric, and a hairy regular black hole solution obtained via gravitational decoupling. Our results reveal clear imprints of both the RZ parametrization coefficients and the hairy black hole parameter on the deflection angle. Furthermore, we assess the viability of using the RZ parametrization to mimic the regular hairy black hole, discussing the validity and limitations of such an approximation.