ShapePipe：一种新的形状测量管道和弱透镜在UNIONS/CFIS数据中的应用
ShapePipe: a new shape measurement pipeline and weak-lensing application to UNIONS/CFIS data
摘要：
UNIONS是一项持续的合作，将提供迄今为止最大的四个光学波段的北方天空深度光度测量。作为这项合作的一部分，CFIS正在获取$r$波段的数据，其平均视宁度为0.65角秒，完整的星等为24.5，因此是弱透镜研究的理想选择。我们进行了第一次弱透镜分析CFIS $r$波段数据在一个地区跨越1700度的天空$^2$。我们创建了一个具有4000万个星系的测量形状的目录，对应于每平方弧分6.8个星系的有效密度，并展示了低水平的系统偏差。这项工作作为进一步的宇宙学研究的基础，使用完整的联合调查4800度$^2$完成后。在这里，我们提出了Shapepipe，一个新开发的弱透镜管道。这条管道使用了最先进的方法，如Ngmix，用于精确的星系形状测量。使用元校准进行剪切校准。我们对点扩散函数（PSF）和星系形状进行了广泛的验证测试。此外，我们创建逼真的图像模拟，以验证估计的剪切。我们量化的PSF模型的准确性，并表明系统的水平是低的PSF残差测量。它们对剪切两点关联函数的影响与<100弧分的角尺度上的宇宙学贡献相比是次主导的。加性剪切偏差低于5 x $10^{-4}$，残留乘性剪切偏差至多为$10^{-3}$，如在图像模拟上测量的。使用COSEBI，我们表明，有没有显着的B-模式存在于二阶剪切统计。我们目前的收敛图，并看到明确的相关性的E-模式与已知的集群位置。我们测量了普朗克集团周围的堆叠切向剪切剖面的显着性高于$4σ$。
英文摘要：
UNIONS is an ongoing collaboration that will provide the largest deep photometric survey of the Northern sky in four optical bands to date. As part of this collaboration, CFIS is taking $r$-band data with an average seeing of 0.65 arcsec, which is complete to magnitude 24.5 and thus ideal for weak-lensing studies. We perform the first weak-lensing analysis of CFIS $r$-band data over an area spanning 1700 deg$^2$ of the sky. We create a catalogue with measured shapes for 40 million galaxies, corresponding to an effective density of 6.8 galaxies per square arcminute, and demonstrate a low level of systematic biases. This work serves as the basis for further cosmological studies using the full UNIONS survey of 4800 deg$^2$ when completed. Here we present ShapePipe, a newly developed weak-lensing pipeline. This pipeline makes use of state-of-the-art methods such as Ngmix for accurate galaxy shape measurement. Shear calibration is performed with metacalibration. We carry out extensive validation tests on the Point Spread Function (PSF), and on the galaxy shapes. In addition, we create realistic image simulations to validate the estimated shear. We quantify the PSF model accuracy and show that the level of systematics is low as measured by the PSF residuals. Their effect on the shear two-point correlation function is sub-dominant compared to the cosmological contribution on angular scales <100 arcmin. The additive shear bias is below 5x$10^{-4}$, and the residual multiplicative shear bias is at most $10^{-3}$ as measured on image simulations. Using COSEBIs we show that there are no significant B-modes present in second-order shear statistics. We present convergence maps and see clear correlations of the E-mode with known cluster positions. We measure the stacked tangential shear profile around Planck clusters at a significance higher than $4σ$.
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