用傅里叶变换加速2点和3点星系关联函数
Accelerating the 2-point and 3-point galaxy correlation functions using Fourier transforms
摘要：
虽然傅立叶变换（FT）是用于寻找关联函数的常用技术，但是它们通常不用于计算广角测量中关于视线的两点关联函数（2PCF）的各向异性，因为视线方向在笛卡尔网格上不是恒定的。在这里，我们将展示如何FT可以用来计算各向异性2PCF的多极矩。我们还展示了如何使用FT来加速Slepian & Eisenstein（2015）的3PCF算法。在这两种情况下，这些FT方法允许避免对计数的计算成本，其比例为调查中对象的数量密度的平方。随着即将到来的DESI，Euclid和LSST的大型数据集，FT技术将为简单的配对或三重计数提供重要的补充。
英文摘要：
Though Fourier Transforms (FTs) are a common technique for finding correlation functions, they are not typically used in computations of the anisotropy of the two-point correlation function (2PCF) about the line of sight in wide-angle surveys because the line-of-sight direction is not constant on the Cartesian grid. Here we show how FTs can be used to compute the multipole moments of the anisotropic 2PCF. We also show how FTs can be used to accelerate the 3PCF algorithm of Slepian & Eisenstein (2015). In both cases, these FT methods allow one to avoid the computational cost of pair counting, which scales as the square of the number density of objects in the survey. With the upcoming large datasets of DESI, Euclid, and LSST, FT techniques will therefore offer an important complement to simple pair or triplet counts.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
