Higher-order geometrical optics for electromagnetic waves on a curved spacetime

Understand

We study the geometrical-optics expansion for circularly-polarized electromagnetic waves propagating on a curved spacetime in general relativity.

• We show that higher-order corrections to the Faraday and stress-energy tensors may be found via a system of transport equations, in principle.
• At sub-leading order, the stress-energy tensor possesses terms proportional to the wavelength whose sign depends on the handedness of the circular polarization.
• Due to such terms, the direction of energy flow is not aligned with the gradient of the eikonal phase, in general, and the wave may carry a transverse stress.