Galaxy clusters identified with optical imaging tend to suffer from projection effects, which impact richness (the number of member galaxies in a cluster) and lensing coherently. Physically unassociated galaxies can be mistaken as cluster members due to the significant uncertainties in their line-of-sight distances, thereby changing the observed cluster richness; at the same time, projection effects alter the weak gravitational lensing signals of clusters, leading to a correlated scatter between richness and lensing at a given halo mass. As a result, the lensing signals for optically selected clusters tend to be biased high. This optical selection bias problem of cluster lensing is one of the key challenges in cluster cosmology. Fortunately, recently available multiwavelength observations of clusters provide a solution. We analyze a simulated dataset mimicking the observed lensing of clusters identified by both optical photometry and gas properties, aiming to constrain this selection bias. Assuming a redMaPPer sample from the Dark Energy Survey with South Pole Telescope Sunyaev-Zeldovich effect observations, we find that an overlapping survey of 1300  deg2, 0.2<𝑧<0.65, can constrain the average lensing bias to an accuracy of 5%. This provides an exciting opportunity for directly constraining optical selection bias from observations. We further show that our approach can remove the optical selection bias from the lensing signal, paving the way for future optical cluster cosmology analyses.

中文翻译：

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利用多波长数据预测星系团透镜对光学选择偏差和投影效应的约束


用光学成像识别的星系团往往会受到投影效应的影响，这种效应会连贯地影响丰富度（星系团中成员星系的数量）和透镜效应。由于视线距离的显著不确定性，物理上没有关联的星系可能会被误认为是星系团成员，从而改变观测到的星系团丰富度;同时，投影效应改变了星团团的微弱引力透镜信号，导致在给定的光晕质量下，丰富度和透镜之间的相关散射。因此，光学选择簇的透镜信号往往偏高。星团透镜的光学选择偏差问题是星团宇宙学中的关键挑战之一。幸运的是，最近可用的星团多波长观测提供了一个解决方案。我们分析了一个模拟数据集，模拟了通过光学光度法和气体特性识别的星团的观测透镜，旨在限制这种选择偏差。假设来自南极望远镜 Sunyaev-Zeldovich 效应观测的暗能量巡天样本，我们发现 1300 度2 的重叠巡天，0.2<z<0.65，可以将平均透镜偏差限制在 5% 的精度。这为直接限制观测的光学选择偏差提供了一个令人兴奋的机会。我们进一步表明，我们的方法可以消除透镜信号中的光学选择偏差，为未来的光学集群宇宙学分析铺平了道路。