Gravitational birefringence of light in Schwarzschild spacetime

Christian Duval (1, 2) , Loïc Marsot (1, 2) , Thomas Schucker (1, 2)

1 CPT - Centre de Physique Théorique - UMR 7332
2 CPT - E2 Géométrie, Physique et Symétries

We compute the gravitational birefringence of light as it undergoes gravitational lensing. To this end we rederive the Souriau-Saturnini equations in the Schwarzschild metric and solve them numerically and perturbatively. Our main result is an offset between the trajectories of the photons of opposite polarizations, which grows with time. We also find an intriguing instability of the spin component transverse to the momentum.

Mots clés: General relativity; alternative theories of gravity; space-time: Schwarzschild; metric: Schwarzschild; photon: trajectory; gravitation: lens; birefringence; polarization; transverse; stability; spin; field equations: solution; perturbation; numerical calculations

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]; Physique des Hautes Energies - Théorie [hep-th]

Christian Duval, Loïc Marsot, Thomas Schucker. Gravitational birefringence of light in Schwarzschild spacetime. Physical Review D, 2019, 99 (12), pp.124037. ⟨10.1103/PhysRevD.99.124037⟩. ⟨hal-01965325⟩