Gravitational Faraday effect from on-shell amplitudes

A bstract Effects of massive object’s spin on massive-massless 2 → classical scattering is studied. Focus set the less-considered dimensionless expansion parameter λ/b , where λ massless particle’s wavelength and b impact parameter. Corrections in start to appear from $$ \mathcal{O} O ( G ), with leading correction terms tied gravitational Faraday effect, which a special case Lense-Thirring effect. We compute eikonal phase up ) extract effect angle time delay 14th order spin. The at linear [1] reproduced by terms, we higher orders find that equivalence principle, or universality, holds NLO for general spinning bodies, i.e. away geometric optics limit. Furthermore, black hole limit, confirm absence particular structure observed [2–8], along associated shift symmetry [7], argue it arbitrary probe