傅立叶空间重构
Reconstruction in Fourier space
摘要：
我们提出了一种快速迭代FFT为基础的重建算法，允许非并行红移空间失真（RSD）。我们测试我们的算法N体暗物质模拟和模拟分布的星系设计复制星系调查条件。我们比较螺线管和无旋分量的红移失真，并表明，这种失真的近似导致更好的估计的真实空间的潜力（因此更快的收敛）比忽略RSD估计位移场时。当我们从RSD的近似值开始时，我们的迭代重建方案在两次迭代中收敛于对应于BOSS CMASS DR 11的模拟样本。该计划需要六次迭代时，从红移空间的过密度测量的初始估计，没有RSD校正。对于覆盖天空上较大角度的观测，预期收敛较慢。我们表明，这种基于FFT的方法提供了一个更好的估计比配置空间的方法，使用有限差分例程来计算潜在的相同的网格分辨率的真实空间位移场。最后，我们表明，对数正态变换的密度，作为一个代理的线性密度，是有益的，在估计完整的位移场从一个密集的样本示踪剂。然而，对数正态变换的过密度不执行时，估计从稀疏模拟与更现实的星系密度的位移。
英文摘要：
We present a fast iterative FFT-based reconstruction algorithm that allows for non- parallel redshift-space distortions (RSD). We test our algorithm on both N-body dark matter simulations and mock distributions of galaxies designed to replicate galaxy survey conditions. We compare solenoidal and irrotational components of the redshift distortion and show that an approximation of this distortion leads to a better estimate of the real-space potential (and therefore faster convergence) than ignoring the RSD when estimating the displacement field. Our iterative reconstruction scheme converges in two iterations for the mock samples corresponding to BOSS CMASS DR11 when we start with an approximation of the RSD. The scheme takes six iterations when the initial estimate, measured from the redshift-space overdensity, has no RSD correction. Slower convergence would be expected for surveys covering a larger angle on the sky. We show that this FFT based method provides a better estimate of the real space displacement field than a configuration space method that uses finite difference routines to compute the potential for the same grid resolution. Finally we show that a lognormal transform of the overdensity, used as a proxy for the linear overdensity, is beneficial in estimating the full displacement field from a dense sample of tracers. However the lognormal transform of the overdensity does not perform well when estimating the displacements from sparser simulations with a more realistic galaxy density.
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