论文标题
剪切测量中像素化效应的公差
Tolerance For the Pixelation Effect in Shear Measurement
论文作者
论文摘要
空间望远镜拍摄的图像通常具有出色的空间分辨率，但是由于有限的CCD像素大小，采样率相对较差。超出了Nyquist极限，不确定像素化效应可能会影响星系形状测量的准确性。鉴于计划了许多基于空间的大规模弱透镜调查，因此及时研究了这个问题。使用Fourier_quad方法，我们将剪切恢复误差量化为采样因子Q的函数，即，对于不同大小和噪声水平的不同PSFS和GALAXIES，点传播功能（PSF）的FWHM与CCD的Pixel大小之间的比率。我们表明，使用$ Q \ lyssim 2 $的单曝光图像可以实现剪切恢复的次级级别精度。该结论适用于比PSF小得多的星系，以及具有显着噪声水平的星系。
Images taken by space telescopes typically have a superb spatial resolution, but a relatively poor sampling rate due to the finite CCD pixel size. Beyond the Nyquist limit, it becomes uncertain how much the pixelation effect may affect the accuracy of galaxy shape measurement. It is timely to study this issue given that a number of space-based large-scale weak lensing surveys are planned. Using the Fourier_Quad method, we quantify the shear recovery error as a function of the sampling factor Q, i.e., the ratio between the FWHM of the point-spread-function (PSF) and the pixel size of the CCD, for different PSFs and galaxies of different sizes and noise levels. We show that sub-percent-level accuracy in shear recovery is achievable with single-exposure images for $Q\lesssim 2$. The conclusion holds for galaxies much smaller than the PSF, and those with a significant level of noise.
