Galaxy shear estimation from stacked images
Galaxy shear estimation from stacked images
复制标题
从堆叠图像估计星系剪切力
DOI：
10.1111/j.1365-2966.2009.15161.x
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发表时间：
2009
影响因子：
4.8
通讯作者：
A. Lewis
中科院分区：
文献类型：
--
作者：
A. Lewis
如果可以准确估计星系剪切力，则星系弱透镜效应的统计数据可以用来约束宇宙学。一般来说，这需要对无透镜星系形状和点扩散函数（PSF）进行精确建模。我讨论了通过堆叠图像来估计星系剪切力的次优但可能稳健的方法，使得堆叠图像分布根据中心极限定理接近高斯分布。然后可以通过径向拟合来确定剪切力，只需要精确的 PSF 模型，而不需要对每个星系进行精确建模。当噪声很大时，必须纠正质心的不对称误差，但当存在具有恒定剪切力的高星系密度时，该方法最终可能能够给出准确的无偏差结果。它为更优化的方法提供了有用的基线，并为估计偏差提供了测试用例，尽管该方法并不直接适用于实际数据。我在 GREAT08 项目提供的具有恒定 PSF 和剪切力的简单玩具模拟上测试了堆叠方法，大多数其他现有方法在该模拟上的表现明显较差，并简要讨论了对更现实情况的概括。在附录中，我讨论了一个简单的分析星系种群模型，其中堆叠在完美的理想情况下给出了最佳误差。
Statistics of the weak lensing of galaxies can be used to constrain cosmology if the galaxy shear can be estimated accurately. In general, this requires accurate modelling of unlensed galaxy shapes and the point spread function (PSF). I discuss suboptimal but potentially robust methods for estimating galaxy shear by stacking images such that the stacked-image distribution is closely Gaussian by the central limit theorem. The shear can then be determined by radial fitting, requiring only an accurate model of the PSF rather than also needing to model each galaxy accurately. When noise is significant, asymmetric errors in the centroid must be corrected, but the method may ultimately be able to give accurate unbiased results when there is a high galaxy density with constant shear. It provides a useful baseline for more optimal methods, and a test case for estimating biases, though the method is not directly applicable to realistic data. I test stacking methods on the simple toy simulations with constant PSF and shear provided by the GREAT08 project, on which most other existing methods perform significantly more poorly, and briefly discuss generalizations to more realistic cases. In the Appendix, I discuss a simple analytic galaxy population model where stacking gives optimal errors in a perfect ideal case.
DOI：
10.1111/j.1365-2966.2006.11315.x
发表时间：
2006-08
影响因子：
4.8
作者：
R. Massey;C. Heymans;J. Bergé;G. Bernstein;S. Bridle;D. Clowe;H. Dahle;R. Ellis;T. Erben
通讯作者：
R. Massey;C. Heymans;J. Bergé;G. Bernstein;S. Bridle;D. Clowe;H. Dahle;R. Ellis;T. Erben
DOI：
10.1111/j.1365-2966.2006.10198.x
发表时间：
2006-05-21
影响因子：
4.8
作者：
Heymans, C;Van Waerbeke, L;Wittman, D
通讯作者：
Wittman, D