Beyond the Detector Horizon: Forecasting Gravitational-Wave Strong Lensing

When gravitational waves pass near massive astrophysical objects, they can be gravitationally lensed. The lensing split them into multiple wave fronts, magnify them, or imprint beating patterns on the waves. Here we focus images produced by strong lensing. In particular, investigate forecasts, rate of lensing, and role statistics in searches. Overall, find a reasonable lensed detections for double, triple, quadruple at LIGO–Virgo–KAGRA design sensitivity. We also report rates A+ LIGO Voyager briefly comment potential improvements due to inclusion subthreshold triggers. that most galaxy-lensed events originate from redshifts z ? 1–4 expected distribution parameters observed events. Besides forecasts searches, which explore repeated event pairs. One problem associated with searches is rising number pairs, leads rapidly increasing false alarm probability. show how knowledge galaxy-lensing time delays our allow us tackle this problem. Once are included, probability increases linearly (similar nonlensed searches) instead quadratically time, significantly improving search. For galaxy cluster lenses, improvement less significant. main uncertainty these merger-rate density estimates high redshift, may better resolved future.