Gravitational Glint: detectable signals from gravitational scattering off the geometry of the Universe

by Prof. Glenn Starkman (Case Western Reserve University (Cleveland, OH, USA))

Tuesday 11 Mar 2025, 11:30 → 12:30 Europe/Rome

1/1-2 - Aula "C. Voci" (Dipartimento di Fisica e Astronomia - Edificio Marzolo)

It has long been expected mathematically that, when electromagnetic or gravitational waves travel through vacuum in a generic non-flat spacetime, the waves develop "tails" that travel more slowly. This can be understood as due to the scattering of the waves off of perturbations in the geometry. The associated signal has been thought to be undetectably weak.  For electromagnetic waves the challenge is exacerbated by the plasma-frequency of the solar system, which screens long-wavelength signals, and by the absence of known high-curvature transparent perturbers.  For gravitational waves, the situation seems more promising, and gravitational waves should be efficiently scattered by the curvature sourced by ordinary compact objects -- stars, white dwarfs, neutron stars, and planets -- and certain candidates for dark matter. The resulting "gravitational glint" should be detectable, and be recognizable  as briefly delayed or angularly separated echoes of the primary signal.  I will mention some puzzles and some potential opportunities.