Cosmic variance of weak lensing surveys in the non‐Gaussian regime
Cosmic variance of weak lensing surveys in the non‐Gaussian regime
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DOI：
10.1111/j.1745-3933.2006.00266.x
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发表时间：
2006-06
影响因子：
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通讯作者：
E. Semboloni;L. Waerbeke;C. Heymans;T. Hamana;S. Colombi;M. White;Y. Mellier
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文献类型：
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作者：
E. Semboloni;L. Waerbeke;C. Heymans;T. Hamana;S. Colombi;M. White;Y. Mellier
弱引力透镜分析的结果受到宇宙方差误差项的影响，该误差项以前是假设高斯统计估计的。在这封信中，我们解决的问题，估计宇宙方差误差弱透镜调查在非高斯制度。利用标准冷暗物质模型的射线追踪模拟（Ωm= 0.3，ΩΛ= 0.7，h= 0.7，σ8= 1），对不同的观测红移zs，我们确定了在64条独立视线上测量的两点切变相关函数的方差。我们比较测量的方差，预期从随机高斯场的方差，并推导出一个红移依赖的非高斯校准关系。我们发现，在1弧分的非高斯和高斯方差之间的比率可以高达30的调查与源红移zs <$0.5和10的zs <$1。当zs ≥ 0.5时，转变尺度为Δ c ≤ 20 arcmin;当zs ≥ 1时，转变尺度为Δ c ≤ 10 arcmin。我们提供拟合公式，我们的结果允许估计非高斯宇宙方差误差，并讨论对当前和未来的调查的影响。然而，需要一组更广泛的模拟来研究我们的结果对宇宙学的依赖性，特别是对集群的幅度。
The results from weak gravitational lensing analyses are subject to a cosmic variance error term that has previously been estimated assuming Gaussian statistics. In this Letter we address the issue of estimating cosmic variance errors for weak lensing surveys in the non-Gaussian regime. Using standard cold dark matter model ray-tracing simulations characterized by Ωm= 0.3, ΩΛ= 0.7, h= 0.7 and σ8= 1 for different survey redshifts zs, we determine the variance of the two-point shear correlation function measured across 64 independent lines of sight. We compare the measured variance to the variance expected from a random Gaussian field and derive a redshift-dependent non-Gaussian calibration relation. We find that the ratio between the non-Gaussian and Gaussian variance at 1 arcmin can be as high as ∼30 for a survey with source redshift zs∼ 0.5 and ∼10 for zs∼ 1. The transition scale ϑc above which the ratio is consistent with unity is found to be ϑc∼ 20 arcmin for zs∼ 0.5 and ϑc∼ 10 arcmin for zs∼ 1. We provide fitting formulae to our results permitting the estimation of non-Gaussian cosmic variance errors, and discuss the impact on current and future surveys. A more extensive set of simulations will, however, be required to investigate the dependence of our results on cosmology, specifically on the amplitude of clustering.