2025/02/02 by Sudhir Gholap, Gholap, Sudhir, Kanchan Soni +5 · 1 citation
Physics and Astronomy · #Pulsars and Gravitational Waves Research #Statistical Mechanics and Entropy #Cosmology and Gravitation Theories
paper · pdf · doi:10.1103/skdj-z7d8
Gravitational waves (GWs) emanated by stellar mass compact binary coalescences (CBCs), and lensed by galaxy- or cluster-scale lenses, will produce two or more copies of the GW signal. These will have identical phase evolution but differing amplitudes. Such lensing signatures are expected to be detected by the end of the LIGO-Virgo-Kagra's (LVK's) fifth observing run (O5). In this work, we propose a novel χlens2 statistic to segregate pairs of detected GW events as either lensed or unlensed, using templates typically used in GW searches. The statistic is an application of the generalized χ2 discriminator described in \citetdhurandhar2017, tailored to probe the similarity (or lack thereof) between the phase evolutions of two CBC signals. We assess the performance of χlens2 on a realistic astrophysical dataset of lensed and unlensed CBCs detectable in O4, assuming a single LIGO-like detector at design sensitivity. We find that we can correctly identify lensed events with efficiencies comparable to existing Bayesian and machine learning methods. Evaluating χlens2 is orders of magnitude faster than Bayesian methods. Moreover, the statistics of χlens2, in stationary Gaussian noise, are fully understood, in contrast to machine learning methods. χlens2 can, therefore, be used to rapidly and accurately weed out the vast majority of unlensed candidate pairs and identify lensed pairs.