弱引力透镜形变信号及其图像精确处理

发布时间：2018-11-27 10:33

【摘要】：弱引力透镜形变信号的测量需要精确的图像处理,因为信号本身非常弱,椭率变化大小只有千分之几的强度,是其星系本身的内禀椭率形状噪音的几百分之一,需要叠加至少约1000幅图像才能从星系图像中得到信号。此外,观测设备的光学效应、大气扰动和CCD的像素化效应(点扩散函数)是图像处理的首要系统误差。怎样改正点扩散函数(PSF)的系统误差是弱引力图像处理的第一步,也是最重要的一步。首先详细介绍了引力透镜的基础理论和弱引力透镜作为其分支领域的特点。其次,介绍了基于重高斯化和圆化卷积核方法的图像处理管线的建立,利用Mandelbaum等人的图像模拟软件,将COSMOS的高分辨率空间图像变成低分辨率地面SDSS图像。最后,检验结果表明,对于一个椭率约为0.05的可加PSF系统误差,经过修正后,只有10~(-4)量级的残余;而PSF的另一个可乘系统误差则修正到1%以下。
[Abstract]:The measurement of a weak gravitational lens deformation signal requires accurate image processing because the signal itself is very weak, with a variation in ellipticity of only a few tenths of its intensity, which is about 1% of the intrinsic ellipticity shape noise of its galaxy itself. At least 1000 images need to be superimposed to get signals from galactic images. In addition, optical effects, atmospheric disturbances and pixel effects of CCD (point diffusion function) are the primary systematic errors in image processing. How to correct the systematic error of (PSF) is the first and most important step in image processing of weak gravity. Firstly, the basic theory of gravitational lensing and the characteristics of weak gravitational lensing as a branch field are introduced in detail. Secondly, the establishment of image processing pipeline based on the methods of heavy Gao Si and circular convolution kernel is introduced. The high-resolution spatial image of COSMOS is transformed into low-resolution ground SDSS image by using the image simulation software of Mandelbaum et al. Finally, the test results show that the error of an additive PSF system with ellipticity about 0.05 is only 10 ~ (-4) residual after correction, while the error of another multiplicative system of PSF is corrected to less than 1%.
【作者单位】：中国科学院上海天文台星系与宇宙学重点实验室;中国科学院大学;
【基金】：国家自然科学基金(10925314,11128306,11121062,11233005) 中科院“宇宙结构起源战略”研究计划(XDB09000000)
【分类号】：P142

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