Interference signatures on gravitational wave signals by compact gravitational lenses

Abstract: The gravitational lensing effect, which distorts and magnifies light as it travels close to the potential of massive objects, is also expected to affect gravitational waves (GWs). These distortions can provide information on the massive objects as lenses, such as invisible black holes (BHs). In this talk, I will describe the lensing signatures due to diffraction and interference, which are relevant effects in GWs due to their coherence and long wavelengths. In particular, the characteristic imprint of interference on GW signals carries information on the lensing system, such as the mass of the lens. We will see which conditions affect the detectability of diffraction and interference in ground-based GW detectors (LIGO-Virgo-KAGRA and Einstein Telescope). I will also describe a novel lensing signature on a stellar-mass BH binary GW source orbiting a massive BH lens. The characteristic signature of the moving GW source encodes its orbital distance to the massive BH lens. Simultaneously obtaining the orbital distance and the mass of the BH lens can help constrain the astrophysical environments where GW signals come from.