Weak gravitational lensing with deimos
Weak gravitational lensing with deimos
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DOI：
10.1111/j.1365-2966.2010.17875.x
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发表时间：
2010-08
影响因子：
4.8
通讯作者：
Peter Melchior;M. Viola;B. M. Schafer;M. Bartelmann
中科院分区：
文献类型：
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作者：
Peter Melchior;M. Viola;B. M. Schafer;M. Bartelmann
我们引入了一种用于弱透镜测量的新方法，该方法基于从望远镜的点扩散函数（PSF）对星系表观亮度分布矩进行数学上精确的反卷积。没有对星系或 PSF 的形状做出任何假设。 （反）卷积方程仅对于未加权矩是精确的，而在实践中，需要将紧凑的权重函数应用于噪声图像以确保矩测量产生显着的结果。我们采用高斯权重函数，其质心和椭圆度被迭代调整以匹配源的相应量。然后，可以通过考虑同一源的高阶加权矩来校正由应用权重函数引起的矩的变化。由于反卷积方程的形式，如果使用相同大小的权重函数来测量星系和 PSF，即使不完整的加权校正也会产生出色的剪切估计。我们通过一系列专门测试证明了这种新方法在弱引力透镜测量背景下的准确性和功能，并展示了其在 GREAT08 Challenge 数据上的竞争性能。可以向作者索取该方法的完整 C++ 实现。
We introduce a novel method for weak-lensing measurements, which is based on a mathematically exact deconvolution of the moments of the apparent brightness distribution of galaxies from the telescope's point spread function (PSF). No assumptions on the shape of the galaxy or the PSF are made. The (de)convolution equations are exact for unweighted moments only, while in practice a compact weight function needs to be applied to the noisy images to ensure that the moment measurement yields significant results. We employ a Gaussian weight function, whose centroid and ellipticity are iteratively adjusted to match the corresponding quantities of the source. The change of the moments caused by the application of the weight function can then be corrected by considering higher order weighted moments of the same source. Because of the form of the deconvolution equations, even an incomplete weighting correction leads to an excellent shear estimation if galaxies and PSF are measured with a weight function of identical size. We demonstrate the accuracy and capabilities of this new method in the context of weak gravitational lensing measurements with a set of specialized tests and show its competitive performance on the GREAT08 Challenge data. A complete c++ implementation of the method can be requested from the authors.