Leveraging the null stream to detect strongly lensed gravitational waves

Gravitational lensing of gravitational waves is expected to be observed in current and future detectors. In view of the growing number of detections, computationally light pipelines are needed. Detection pipelines used in past LIGO-Virgo-KAGRA searches for strong lensing require parameter estimation to be performed on the gravitational wave signal or are machine learning based. Removing the need for parameter estimation in classical methods would alleviate the ever growing demand of computational resources in strong lensing searches and would make real-time analysis possible. We present a novel way of identifying strongly lensed gravitational wave signals, based on the null stream of a detector network. We lay out the basis for this detection method and show preliminary results confirming the validity of the formalism. We also discuss the next development steps, including how to make it independent of parameter estimation.