Gravitational lensing and microlensing of gravitational-waves

随着地面探测器网络变得更加敏感，双黑洞或中子星合并的引力透镜将变得越来越有可能-并且将提供对强引力的重要进一步探测和约束透镜特性的新方法。先前有相当成熟的文献探索透镜引力波源的理论特征，LIGO Virgo KAGRA （LVK）合作项目已经投入了大量精力来建立分析管道，以搜索透镜信号，并有几篇简短的作者或合作论文展示了这些搜索的结果。然而，许多代码基础设施都集中在点质量透镜上，特别是对于微透镜事件。虽然这是一个合理的假设，但比较不同扩展透镜质量分布的结果是一个重要而及时的机会。该项目的目的是开发新的分析方法，考虑不同的透镜模型，有效地计算它们的透镜放大函数，并允许贝叶斯模型比较它们对候选信号的相对适用性。执行这些计算的代码将被整合到LVK透镜管道中，经过彻底测试并应用于未来LVK观测运行的数据。此外，我们亦会探讨如何更广泛地适用于第三代地面探测器的数据。这项工作的最终目标将是允许对透镜引力波事件进行更可靠的检测，并对透镜特性进行更完整的研究。

As the network of ground-based detectors becomes more sensitive, the gravitational lensing of binary black hole or neutron star merger will become increasingly likely - and will offer both an important further probe of strong gravity and a novel means of constraining the properties of the lens. There is a reasonably mature prior literature exploring the theoretical signatures of lensed gravitational-wave sources, and the LIGO Virgo KAGRA (LVK) Collaborations have already invested significant effort in setting up analysis pipelines to search for lensed signals, with several short-author or collaboration papers presenting the results of those searches. Much of the code infrastructure has focussed on point-mass lenses, however, particularly for microlensing events. While that is partially justified as a reasonable assumption, the opportunity to compare results for different extended lens mass distributions is an important and timely one. The aim of this project is to develop new analysis approaches that consider different lens models, efficiently compute their lensing amplification functions and permit a Bayesian model comparison of their relative applicability to candidate signals. The codes to carry out these calculations will be incorporated into the LVK lensing pipelines, thoroughly tested and applied to data from future LVK observing runs. Wider applicability of the lensing codes to e.g. data from 3rd generation ground-based detectors will also be explored. The ultimate goal of this work will be to allow a more robust detection of a lensed gravitational-wave event and a more complete investigation of the lens properties.