Vacuum polarization effects in the background of a deformed compact object and implications for photon velocity

TL;DR

This paper investigates how vacuum polarization affects light propagation near deformed compact objects, revealing polarization-dependent photon velocity variations and potential observable effects in astrophysical phenomena like gravitational lensing and shadows.

Contribution

It introduces a model incorporating quadrupole parameters to study QED-induced birefringence effects in deformed compact objects, linking quantum effects with astrophysical observations.

Findings

Photon velocity varies with polarization in deformed spacetime

Gravitational lensing and shadow properties are influenced by quadrupole parameters

Future high-precision observations could detect vacuum birefringence effects

Abstract

This paper studies the impact of vacuum polarization on light propagation in the background of a distorted, deformed compact object. Focusing on a spacetime containing two quadrupole parameters associated with the central object and external fields, we explore how these parameters influence observable effects as dynamical degrees of freedom. In this setup, we investigate electromagnetic birefringence, noting distinct polarization-dependent photon velocity variations and gravitational lens effects. Although current resolution may limit detection, future high-precision observations could reveal these quantum electrodynamics (QED) induced birefringence effects, advancing our understanding of vacuum birefringence in astrophysical contexts. We further analyze the dependence of shadow properties on the model's variables, using observational data from Sgr A*.