The assumptions of large-scale homogeneity and isotropy underly the familiar Friedmann-Lemaître-Robertson-Walker (FLRW) metric that appears to be an accurate description of our Universe. In this paper, we propose a new strategy of testing the validity of the FLRW metric, based on the galactic-scale lensing systems where strongly lensed gravitational waves and their electromagnetic counterparts can be simultaneously detected. Each strong lensing system creates opportunity to infer the curvature parameter of the Universe. Consequently, combined analysis of many such systems will provide a model-independent tool to test the validity of the FLRW metric. Our study demonstrates that the third-generation ground based GW detectors, like the Einstein Telescope (ET) and space-based detectors, like the Big Bang Observer (BBO), are promising concerning determination of the curvature parameter or possible detection of deviation from the FLRW metric. Such accurate measurements of the FLRW metric can become a milestone in precision GW cosmology.
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机译：大规模同质性和各向同性的假设在人们熟悉的Friedmann-Lemaître-Robertson-Walker（FLRW）度量标准之下，该度量标准似乎是对我们宇宙的准确描述。在本文中，我们提出了一种新的策略来测试FLRW度量的有效性，该方法基于银河规模的透镜系统，在该系统中可以同时检测到强透镜引力波及其电磁对应物。每个强大的透镜系统都为推断宇宙的曲率参数创造了机会。因此，对许多此类系统的综合分析将提供独立于模型的工具，以测试FLRW指标的有效性。我们的研究表明，像爱因斯坦望远镜（ET）这样的第三代地面GW探测器，以及像Big Bang Observer（BBO）这样的天基探测器，都有望在确定曲率参数或可能探测到偏离地球的地方FLRW指标。 FLRW度量的这种精确测量可以成为精密GW宇宙学的一个里程碑。
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