在黑暗中看到--我。多纪元炼金术
Seeing in the dark -- I. Multi-epoch alchemy
摘要：
由于和谐宇宙学的大部分能量密度都是不可见的，因此大尺度结构的弱透镜效应是一种非常宝贵的宇宙学工具。在未来十年，几个大型地面成像调查将试图测量这种影响，但对大气湍流和望远镜光学系统引入的虚假透镜信号的可靠控制仍然是一个具有挑战性的问题。我们解决这一挑战的演示，点扩散函数（PSF）的影响，在目前的地面调查测量星系的形状可以纠正与现有的分析技术。在这项工作中，我们共同添加现有的斯隆数字巡天成像的赤道条纹，以建立一个数据集的统计能力来测量宇宙剪切，同时使用舍入核方法来抵消各向异性PSF的影响。我们建立了一个星系目录的组合成像，它的光度特性，并表明，在这个目录的PSF校正后的虚假剪切剩余相比，预期的宇宙剪切信号可以忽略不计。我们确定了一个新的来源的系统误差剪切自相关性所产生的选择偏差掩蔽。最后，我们讨论的情况下，这种方法预计将是有用的，即将到来的地面调查，透镜作为科学目标之一，并确定系统误差，可以降低其功效。
英文摘要：
Weak lensing by large-scale structure is an invaluable cosmological tool given that most of the energy density of the concordance cosmology is invisible. Several large ground-based imaging surveys will attempt to measure this effect over the coming decade, but reliable control of the spurious lensing signal introduced by atmospheric turbulence and telescope optics remains a challenging problem. We address this challenge with a demonstration that point-spread function (PSF) effects on measured galaxy shapes in current ground-based surveys can be corrected with existing analysis techniques. In this work, we co-add existing Sloan Digital Sky Survey imaging on the equatorial stripe in order to build a data set with the statistical power to measure cosmic shear, while using a rounding kernel method to null out the effects of the anisotropic PSF. We build a galaxy catalogue from the combined imaging, characterise its photometric properties, and show that the spurious shear remaining in this catalogue after the PSF correction is negligible compared to the expected cosmic shear signal. We identify a new source of systematic error in the shear-shear auto-correlations arising from selection biases related to masking. Finally, we discuss the circumstances in which this method is expected to be useful for upcoming ground-based surveys that have lensing as one of the science goals, and identify the systematic errors that can reduce its efficacy.
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