Speaker
Description
Gravitational waves propagating through the universe inevitably encounter massive objects, getting deflected and magnified. The presence of lenses such as galaxies, clusters, or stars breaks the symmetries of the FLRW metric, allowing for new interactions between different polarizations. These bear the signatures of modified gravity and imprint distinctive effects on the waveforms. I will present the potential of gravitational wave lensing as a testing ground for theories beyond GR, focusing on scalar-tensor theories with screening. These are particularly interesting since screened environments naturally modify GW propagation, while evading local gravity tests. I will focus on a formalism that goes beyond the geometric optics approximation, allowing for lens-induced dispersion, which can constrain any modified theory without the need for EM counterparts.