Dr Justin Janquart (Université Catholique de Louvain)

Like electromagnetic signals, gravitational waves can undergo gravitational lensing when a massive object is present on the path from source to observer. Depending on the lens’ characteristics and the geometry, the effect of the wave can be different. For lower masses and less aligned systems, we can have a single distorted image, called microlensing. When the alignment improves and/or the mass of the lens increases, we can get several, potentially detectable, images, i.e. repeated versions signal with the same frequency evolution. When the time delay between the images is large enough to make them distinct, we call the phenomenon strong lensing, else, it is referred to as millilensing. The forecast detection rate for strong lensing is optimistic, with a real chance to observe strongly-lensed gravitational waves in the coming years. While those for microlensing and millilensing are more uncertain, there is potential that some of the strongly-lensed images also have features related to the other types of lensing. Still, it is possible that these other lensing types are observed in their own right. Here, I present an overview of current gravitational wave lensing searches, presenting some of the related complications and how they can be alleviated.