The impact of non‐Gaussian errors on weak lensing surveys
The impact of non‐Gaussian errors on weak lensing surveys
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DOI：
10.1111/j.1365-2966.2009.14504.x
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发表时间：
2008-10
影响因子：
4.8
通讯作者：
M. Takada;Bhuvnesh Jain Ipmu;U. Tokyo;U. Penn
中科院分区：
文献类型：
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作者：
M. Takada;Bhuvnesh Jain Ipmu;U. Tokyo;U. Penn
弱透镜功率谱通过其对结构生长和几何因子的依赖来携带宇宙学信息。由于大部分宇宙学信息来自受非线性聚类影响的尺度，因此透镜功率谱的测量可能会因非高斯协方差而退化。最近，关于这种退化程度的研究相互矛盾。我们使用晕模型来估计它，包括新的贡献有关的有限大小的透镜调查，以下Rimes和汉密尔顿的三维模拟研究。我们发现，不同的多极子之间的非高斯相关性可以降低功率谱振幅的累积信噪比（S/N）高达2（或5的最坏情况下的模型，超过目前的N体模拟预测）的一个因素。然而，使用八参数Fisher分析，我们发现单个参数的边缘化误差下降不到10%（或最坏情况模型的20%）。参数精度的较小退化主要是因为：高维参数空间中的单个参数的退化远远小于整个Fisher椭球的体积;透镜效应涉及沿视线的沿着投影，这减少了非高斯效应;一些宇宙学信息来自几何因素，这些因素根本不会退化。我们将我们的研究结果与Lee和Pen的研究结果进行了对比，他们认为信息内容的退化要大得多。最后，我们的结果给出了一个有用的指导，探索调查设计的宇宙学信息回报不同的调查面积，深度和一些系统误差的水平。
The weak lensing power spectrum carries cosmological information via its dependence on the growth of structure and on geometric factors. Since much of the cosmological information comes from scales affected by non-linear clustering, measurements of the lensing power spectrum can be degraded by non-Gaussian covariances. Recently, there have been conflicting studies about the level of this degradation. We use the halo model to estimate it and include new contributions related to the finite size of lensing surveys, following Rimes and Hamilton's study of three-dimensional simulations. We find that non-Gaussian correlations between different multipoles can degrade the cumulative signal-to-noise ratio (S/N) for the power spectrum amplitude by up to a factor of 2 (or 5 for a worst-case model that exceeds current N-body simulation predictions). However, using an eight-parameter Fisher analysis, we find that the marginalized errors on individual parameters are degraded by less than 10 per cent (or 20 per cent for the worst-case model). The smaller degradation in parameter accuracy is primarily because: individual parameters in a high-dimensional parameter space are degraded much less than the volume of the full Fisher ellipsoid; lensing involves projections along the line of sight, which reduce the non-Gaussian effect; some of the cosmological information comes from geometric factors which are not degraded at all. We contrast our findings with those of Lee and Pen who suggested a much larger degradation in information content. Finally, our results give a useful guide for exploring survey design by giving the cosmological information returns for varying survey area, depth and the level of some systematic errors.