论文标题
谐波空间星系功率谱中的非线性红移空间变形
Nonlinear Redshift-Space Distortions in the Harmonic-space Galaxy Power Spectrum
论文作者
论文摘要
未来的高光谱分辨率银河系调查将观察到具有几乎全天足迹的星系。因此，为这些调查建模星系聚类，必须包括狭窄的红移箱的广角效应。特别是，当红移箱大小与典型的特殊速度场相媲美时，非线性红移空间失真（RSD）效应就变得很重要。傅立叶空间RSD模型对球形谐波空间的幼稚投影导致表达分歧。在本文中，我们提出了将高阶RSD术语投射到球形谐波空间中的一般形式主义。我们表明，非线性RSD效应，包括GOD-GOD（FOG），完全归因于径向窗口函数的修改。我们发现，尽管线性RSD增强了谐波空间功率谱，但与三维情况不同，但在小角度尺度上，增强量会降低。如果垃圾箱的大小小于$ΔR\lyssimπσ_U$，则GOD的手指在所有横向尺度上都抑制了所有横向尺度的角功率谱；例如，对应于光谱分辨率$ r =λ/δλ$的径向箱大小满足条件。我们还提供了统一的近似值，该近似将完整的计算重现为次级精度。
Future high spectroscopic resolution galaxy surveys will observe galaxies with nearly full-sky footprints. Modeling the galaxy clustering for these surveys, therefore, must include the wide-angle effect with narrow redshift binning. In particular, when the redshift-bin size is comparable to the typical peculiar velocity field, the nonlinear redshift-space distortion (RSD) effect becomes important. A naive projection of the Fourier-space RSD model to spherical harmonic space leads to diverging expressions. In this paper we present a general formalism of projecting the higher-order RSD terms into spherical harmonic space. We show that the nonlinear RSD effect, including the fingers-of-God (FoG), can be entirely attributed to a modification of the radial window function. We find that while linear RSD enhances the harmonic-space power spectrum, unlike the three-dimensional case, the enhancement decreases on small angular-scales. The fingers-of-God suppress the angular power spectrum on all transverse scales if the bin size is smaller than $Δr \lesssim πσ_u$; for example, the radial bin sizes corresponding to a spectral resolution $R=λ/Δλ$ of a few hundred satisfy the condition. We also provide the flat-sky approximation which reproduces the full calculation to sub-percent accuracy.
