Astrophysically-Informed Search of Strongly-Lensed Gravitational-Wave Transients from GWTC-1

When a compact binary merger that LIGO and Virgo see is sufficiently aligned with a gravitational potential such as that from a galaxy or a galaxy cluster at a cosmological distance, strong lensing takes place and multiple copies of the same transient will be registered by GW detectors at separate times and amplitudes as different detections. The relative amplitudes and time delays of these lensed GW signals would depend on the properties of the lens responsible, and would also affect the likelihood ratio that a set of GW signals being lensed "images" coming from the same source, or simply all coming from different sources. In this talk, I will present a search of strongly-lensed GW transients from GWTC-1 that incorporates information about the potential galaxy lenses using a simulated lens catalog, as well as information about the intrinsic properties and the redshift distribution of the GW sources. Selection effects are accounted for in this analysis, which tend to lower the likelihood ratio for the strong lensing hypothesis.