Beyond Limber: efficient computation of angular power spectra for galaxy clustering and weak lensing
Beyond Limber: efficient computation of angular power spectra for galaxy clustering and weak lensing
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DOI：
10.1088/1475-7516/2020/05/010
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发表时间：
2019-11
影响因子：
6.4
通讯作者：
X. Fang;E. Krause;T. Eifler;N. MacCrann
中科院分区：
文献类型：
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作者：
X. Fang;E. Krause;T. Eifler;N. MacCrann
大尺度结构观测量的角两点统计是重要的宇宙学探索。为了达到未来调查的统计精度所需的高精度，这些统计数据中的一些可能需要在没有常用的林伯近似的情况下计算;然而，精确的计算需要在贝塞尔函数上积分，并且蛮力评估收敛缓慢。我们提出了一种新的方法的基础上，我们的广义FFTLog算法的角功率谱的有效计算超出Limber近似。新方法大大简化了计算，提高了数值计算的速度和稳定性.它很容易扩展到处理涉及贝塞尔函数导数的积分，使其同样适用于数值上更具挑战性的情况下，如红移空间失真和多普勒效应的贡献。我们实现了我们的方法，星系聚类和星系-星系透镜功率谱。我们发现，在未来的分析中，如LSST第1年和DES第6年使用Limber近似的星系聚类可能会导致宇宙学参数的显着偏差，这表明超越Limber近似是必要的，这些分析。
Angular two-point statistics of large-scale structure observables are important cosmological probes. To reach the high accuracy required by the statistical precision of future surveys, some of these statistics may need to be computed without the commonly employed Limber approximation; the exact computation however requires integration over Bessel functions, and a brute-force evaluation is slow to converge. We present a new method based on our generalized FFTLog algorithm for the efficient computation of angular power spectra beyond the Limber approximation. The new method significantly simplifies the calculation and improves the numerical speed and stability. It is easily extended to handle integrals involving derivatives of Bessel functions, making it equally applicable to numerically more challenging cases such as contributions from redshift-space distortions and Doppler effects. We implement our method for galaxy clustering and galaxy-galaxy lensing power spectra. We find that using the Limber approximation for galaxy clustering in future analyses like LSST Year 1 and DES Year 6 may cause significant biases in cosmological parameters, indicating that going beyond the Limber approximation is necessary for these analyses.