Frequency- and polarization-dependent lensing of gravitational waves in strong gravitational fields

Understand

The propagation of gravitational waves can be described in terms of null geodesics by using the geometrical optics approximation.

• However, at large but finite frequencies the propagation is affected by the spin-orbit coupling corrections to geometrical optics, known as the gravitational spin Hall effect.
• Consequently, gravitational waves follow slightly different frequency- and polarization-dependent trajectories, leading to dispersive and birefringent phenomena.
• We study the potential for detecting the gravitational spin Hall effect in hierarchical triple black hole systems, consisting of an emitting binary orbiting a more massive body acting as a gravitational lens.