Identifying strong lensing gravitational wave (SLGW) events is of utmost importance in astrophysics as we approach the historic first detection of SLGW amidst the growing number of gravitational wave (GW) events. Currently, one crucial method for identifying SLGW signals involves assessing the overlap of parameters between two GWs. However, the distribution of discrete matter, such as stars and sub-halos, within the strong lensing galaxy can imprint a wave optical (WO) effect on the SLGW waveform. These frequency dependent imprints introduce biases in parameter estimation and impact SLGW identification. In this study, we assess the influence of the stellar microlensing field embedded in a strong lensing galaxy. Our finding demonstrate that the WO effect reduces the detection efficiency of SLGW by 5%∼50% for various false alarm probabilities per pair (FAPperpair). Specifically, at an FAPperpair of 10−5, the detection efficiency decreases from ∼10% to ∼5%. Consequently, the presence of the microlensing field can result in missing half of the strong lensing candidates. Additionally, the microlensing WO effect introduces a noticeable bias in intrinsic parameters, particularly for chirp mass and mass ratio. However, it has tiny influence on extrinsic parameters. Considering all parameters, ∼30% of events exhibit a 1σ parameter bias, ∼12% exhibit a 2σ parameter bias, and ∼5% exhibit a 3σ parameter bias.
@article{arxiv.2306.14796,
title = {Microlensing bias on the detection of strong lensing gravitational wave},
author = {Xikai Shan and Xuechun Chen and Bin Hu and Guoliang Li},
journal= {arXiv preprint arXiv:2306.14796},
year = {2024}
}