The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations
The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations
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DOI：
10.1111/j.1365-2966.2006.10198.x
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发表时间：
2006-05-21
影响因子：
4.8
通讯作者：
Wittman, D
中科院分区：
文献类型：
--
作者：
Heymans, C;Van Waerbeke, L;Wittman, D
剪切测试计划（STEP）是一个合作项目，旨在提高所有弱透镜测量的准确性和可靠性，为下一代宽场测量做准备。在这第一步文件中，我们提出了一个盲分析的结果，模拟地面观测相对简单的星系形态。最成功的方法是实现百分比级精度。从已被用来约束宇宙学的宇宙剪切管道，我们发现弱透镜剪切测量的准确性，是在统计误差范围内的当前弱透镜分析，剪切测量准确到优于7%.The主导源的测量误差产生的校准不确定性，测量剪切是超过或低估了一个常数乘法因子。这是令人担忧的，因为校准误差无法通过标准诊断测试检测到。测量的校准误差似乎是由于恒星污染，错误的对象检测，剪切测量方法本身，选择偏差和/或使用偏置权重。添加剂系统学（错误检测剪切）造成的残余点扩散函数各向异性，在大多数情况下，减少到低于0.001的等效剪切，一个数量级以下的宇宙剪切变形的规模探测电流survey.Our结果提供了一个快照视图的准确性，目前的地基弱透镜方法和基准，我们可以提高。为此，我们提供了测试的每种方法的描述，并包括常用的凯泽，斯奎尔斯和布罗德赫斯特方法（KSB+）的八种不同的实现细节，以帮助改善未来的KSB+分析。
The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In this first STEP paper, we present the results of a blind analysis of simulated ground-based observations of relatively simple galaxy morphologies. The most successful methods are shown to achieve percent level accuracy. From the cosmic shear pipelines that have been used to constrain cosmology, we find weak lensing shear measured to an accuracy that is within the statistical errors of current weak lensing analyses, with shear measurements accurate to better than 7 per cent. The dominant source of measurement error is shown to arise from calibration uncertainties where the measured shear is over or underestimated by a constant multiplicative factor. This is of concern as calibration errors cannot be detected through standard diagnostic tests. The measured calibration errors appear to result from stellar contamination, false object detection, the shear measurement method itself, selection bias and/or the use of biased weights. Additive systematics (false detections of shear) resulting from residual point-spread function anisotropy are, in most cases, reduced to below an equivalent shear of 0.001, an order of magnitude below cosmic shear distortions on the scales probed by current surveys.Our results provide a snapshot view of the accuracy of current ground-based weak lensing methods and a benchmark upon which we can improve. To this end we provide descriptions of each method tested and include details of the eight different implementations of the commonly used Kaiser, Squires & Broadhurst method (KSB+) to aid the improvement of future KSB+ analyses.