Search for Strongly lensed Gravitational Wave Images
Date:
Abstract: When a gravitational wave passes by a massive object, its trajectory gets curved which can result in multiple images separated by a time delay, a phenomenon known as strong lensing. Although gravitational wave lensing has not been observed yet, it is currently predicted that it will be possible to detect with third-generation detectors. Moreover, the future detectors are expected to significantly increase the gravitational-wave detection rate up to \(O(10^5−10^6)\) \(yr^{−1}\) which could also increase the chance of observing gravitational wave lensing. Therefore, it is necessary to develop accurate and efficient tools to filter potentially lensed gravitational-wave signal pairs. In the study, we propose three statistics to analyze the overlap of two sky localization probability maps, which could provide a quick preliminary lensing analysis of two gravitational-wave signals within 3 seconds. We simulate 200 lensed pairs of gravitational-wave signals for 5 signal-to-noise ratios to investigate the performance of the search methodology. By setting up a threshold with a specific false positive rate \(FPR=10^{−2}\) for the three overlap statistics, we conclude that it is possible to filter out more than 99% of the non-lensed event pairs while keeping all lensed event pairs.