Stellar-mass binary black holes (BBH) may form, evolve, and merge within the dense environments of active galactic nuclei (AGN) discs, thereby contributing to the BBH population detected by gravitational wave (GW) observatories. Mergers occurring in AGN discs may be gravitationally lensed by the central supermassive black hole. Such lensing presents a potential probe of BBH formation channels through its probability. In this work, we calculate the AGN lensing probability of LIGO sources embedded in an AGN disc by relating mismatch threshold to the signal-to-noise ratio. The AGN lensing probability of a GW190521-like event will be $\sim 3\%$ for the O3 power spectral density (PSD), $\sim 6\%$ for the Aplus PSD, and $\sim 33\%$ for the ET PSD. If AGNs are indeed the primary formation channel for BBHs, we could quantify the probability of detecting the lensed GW events in such a scenario. The nondetections, on the other hand, will place stricter constraints on the fraction of AGN disc BBHs and even the birthplaces of BBH mergers.

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• Gravitational lenses
• Gravitational waves