Mapping dark matter on the celestial sphere with weak gravitational lensing
Mapping dark matter on the celestial sphere with weak gravitational lensing
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利用弱引力透镜绘制天球上的暗物质图
DOI：
10.1093/mnras/stab3235
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Antoine Plouviez
中科院分区：
文献类型：
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作者：
C. Wallis;Matthew Alexander Price;J. McEwen;T. Kitching;B. Leistedt;Antoine Plouviez
综合物质分布的收敛图是弱引力透镜调查的关键科学结果。迄今为止，已经使用天球的平面近似来恢复收敛图。然而，随着暗能量实验（例如欧几里德、大型综合巡天望远镜（LSST）和广域红外巡天望远镜（WFIRST））覆盖的天空面积不断增加，这一假设将不再有效。我们将用于恢复收敛场的 Kaiser-Squires 技术（以前仅限于平面）扩展到球面设置。通过模拟，我们研究了平面近似引入的误差。此外，我们研究了如何在平面设置中最好地恢复收敛图，考虑各种不同的投影并定义投影旋转场（例如宇宙剪切）时所需的局部旋转。对于未来勘测中典型的天空覆盖范围，投影效应引入的误差可能达到百分之几十，在某些情况下超过 50%。球极投影是等角投影，因此保留了局部角度，是最有效的平面投影。无论如何，通过直接在天球上恢复会聚场可以完全避免这些错误。我们应用针对公共暗能量巡天 (DES) 科学验证数据提出的球形 Kaiser-Squires 质量绘图方法，直接在天球上恢复收敛图。
Convergence maps of the integrated matter distribution are a key science result from weak gravitational lensing surveys. To date, recovering convergence maps has been performed using a planar approximation of the celestial sphere. However, with the increasing area of sky covered by dark energy experiments, such as Euclid, the Large Synoptic Survey Telescope (LSST), and the Wide Field Infrared Survey Telescope (WFIRST), this assumption will no longer be valid. We extend the Kaiser-Squires technique for recovering convergence fields, restricted previously to the plane, to the spherical setting. Through simulations we study the error introduced by planar approximations. Moreover, we examine how best to recover convergence maps in the planar setting, considering a variety of different projections and defining the local rotations that are required when projecting spin fields such as cosmic shear. For the sky coverages typical of future surveys, errors introduced by projection effects can be of order tens of percent, exceeding 50% in some cases. The stereographic projection, which is conformal and so preserves local angles, is the most effective planar projection. In any case, these errors can be avoided entirely by recovering convergence fields directly on the celestial sphere. We apply the spherical Kaiser-Squires mass-mapping method presented to the public Dark Energy Survey (DES) science verification data to recover convergence maps directly on the celestial sphere.