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arXiv 1104.2596astro-ph.COastro-ph.IM
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对团簇轮廓不确定性的弱透镜质量估计的优化

Optimizing weak lensing mass estimates for cluster profile uncertainty

Daniel Gruen, Gary M. Bernstein, Tsz Yan Lam, Stella Seitz

摘要:

星系团质量的弱透镜测量对于校正质量可观测关系(MORs)以研究结构的生长和暗能量的性质是必要的。然而,所测量的集群剪切信号变化在固定质量M_200米,由于固有的椭圆率的背景星系,沿视线的干预结构,和集群结构的变化,由于分散的浓度,非球面性和子结构。我们使用N体模拟晕来推导和评估弱透镜圆孔质量测量M_ap,该测量在所有这些形式的可变性存在的情况下使质量估计方差<(M_ap -M_200 m)^2>最小化。根据晕质量和观测条件,所得到的质量估计改善M_ap过滤器优化的圆形NFW-配置文件集群中存在的不相关的大尺度结构(LSS)关于后者改善的估计,只最大限度地减少形状噪声的影响。在忽略内部集群结构变化的同时优化不相关的LSS,会对晕核附近的轮廓施加太多权重,在某些情况下甚至可能比根本不考虑LSS更糟糕。我们简要地讨论了集群结构和相关结构的设计和性能的弱透镜调查旨在校准集群MORs的变化的影响。

英文摘要:

Weak lensing measurements of cluster masses are necessary for calibrating mass-observable relations (MORs) to investigate the growth of structure and the properties of dark energy. However, the measured cluster shear signal varies at fixed mass M_200m due to inherent ellipticity of background galaxies, intervening structures along the line of sight, and variations in the cluster structure due to scatter in concentrations, asphericity and substructure. We use N-body simulated halos to derive and evaluate a weak lensing circular aperture mass measurement M_ap that minimizes the mass estimate variance <(M_ap - M_200m)^2> in the presence of all these forms of variability. Depending on halo mass and observational conditions, the resulting mass estimator improves on M_ap filters optimized for circular NFW-profile clusters in the presence of uncorrelated large scale structure (LSS) about as much as the latter improve on an estimator that only minimizes the influence of shape noise. Optimizing for uncorrelated LSS while ignoring the variation of internal cluster structure puts too much weight on the profile near the cores of halos, and under some circumstances can even be worse than not accounting for LSS at all. We briefly discuss the impact of variability in cluster structure and correlated structures on the design and performance of weak lensing surveys intended to calibrate cluster MORs.

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