Weak gravitational lensing shear measurement with FPFS: analytical mitigation of noise bias and selection bias
Weak gravitational lensing shear measurement with FPFS: analytical mitigation of noise bias and selection bias
复制标题
使用 FPFS 进行弱引力透镜剪切测量：噪声偏差和选择偏差的分析缓解
DOI：
10.1093/mnras/stac342
复制
发表时间：
2022
影响因子：
4.8
通讯作者：
Massey Richard
中科院分区：
文献类型：
--
作者：
Li Xiangchong;Li Yin;Massey Richard
专用的“第四阶段”天文台很快将观测整个河外天空，通过弱引力透镜来测量星系形状的“宇宙剪切”扭曲。为了测量这些星系的表观形状，我们提出了傅里叶幂函数 Shapelet (FPFS) 剪切测量方法的改进版本。现在，这包括对困扰所有形状测量算法的偏差来源的分析校正：包括噪声偏差（由于可观测量的非线性组合中的噪声）和选择偏差（由于或多或少可能检测到剪切星系）。至关重要的是，这些分析解决方案不依赖于外部图像模拟的校准。对于孤立星系，小的残余乘性偏差和加性偏差现在满足 IV 阶段实验的科学要求。FPFS 也能准确地处理微弱星系，并能有效防止恒星污染。未来的工作将集中于消除重叠星系的混合。本文使用的代码可以在每 CPU 秒内处理星系图像，可从 https://github.com/mr-superonion/FPFS 获取。
Dedicated ‘Stage IV’ observatories will soon observe the entire extragalactic sky, to measure the ‘cosmic shear’ distortion of galaxy shapes by weak gravitational lensing. To measure the apparent shapes of those galaxies, we present an improved version of the Fourier Power Function Shapelets (FPFS) shear measurement method. This now includes analytic corrections for sources of bias that plague all shape measurement algorithms: Including noise bias (due to noise in non-linear combinations of observable quantities) and selection bias (due to sheared galaxies being more or less likely to be detected). Crucially, these analytic solutions do not rely on calibration from external image simulations. For isolated galaxies, the small residualmultiplicative bias andadditive bias now meet science requirements for Stage IV experiments.FPFSalso works accurately for faint galaxies and robustly against stellar contamination. Future work will focus on deblending overlapping galaxies. The code used for this paper can processgalaxy images per CPU second and is available from https://github.com/mr-superonion/FPFS.