Evolution of LISA Observables for Binary Black Holes Lensed by a Supermassive Black Hole

Abstract Binary black holes (BBHs) are expected to form and merge in active galactic nuclei (AGN), deep in the potential well of a supermassive black hole (SMBH), from populations that exist in a nuclear star cluster. Here we investigate the gravitational-wave (GW) signature of a BBH lensed by a nearby SMBH. For a fiducial GW150914-like BBH orbiting close to a 10 8 M ⊙ SMBH located at z = 0.1, the lensed GW signal varies in a predictable manner in and out of the Laser Interferometer Space Antenna (LISA) detectability band and across frequencies. The occurrence of such signatures has the potential to confound LISA global fit models if they are not modeled. Detection of these sources provides an independent measure of AGN inclination angles, along with detecting warping of the inner disk and measuring the SMBH spin.