论文标题
通过星系调查的统计各向异性的最小差异估计
Minimum variance estimation of statistical anisotropy via galaxy survey
论文作者
论文摘要
我们考虑从星系数密度波动的红移空间相关器和特殊速度场中测量宇宙统计各向异性的好处，而无需采用平行平行（PP）近似。由于相关器使用一般的三极球形谐波（Triposh）基础分解，因此我们可以通过PP近似无法处理广角贡献，同时，可以清洁靶向目标各向异性。我们首次计算三丝分解系数和Fisher矩阵的协方差，以预测统计各向异性的可检测性。协方差的结果表达不含由PP近似引起的每个多极矩之间的非平凡混合，因此可检测性得到了充分优化。与PP近似值下的分析相比，始终确认可检测性的优势，并突出显示，尤其是在射击噪声水平较大的情况下，目标统计各向异性在傅立叶空间中具有蓝色的形状。基于Triposh的分析在即将进行的全天空调查数据中的应用可能会导致对各向异性的限制与当前的宇宙微波背景相比或更紧密。
We consider the benefits of measuring cosmic statistical anisotropy from redshift-space correlators of the galaxy number density fluctuation and the peculiar velocity field without adopting the plane-parallel (PP) approximation. Since the correlators are decomposed using the general tripolar spherical harmonic (TripoSH) basis, we can deal with wide-angle contributions untreatable by the PP approximation, and at the same time, target anisotropic signatures can be cleanly extracted. We, for the first time, compute the covariance of the TripoSH decomposition coefficient and the Fisher matrix to forecast the detectability of statistical anisotropy. The resultant expression of the covariance is free from nontrivial mixings between each multipole moment caused by the PP approximation and hence the detectability is fully optimized. Compared with the analysis under the PP approximation, the superiority in detectability is always confirmed, and it is highlighted, especially in the cases that the shot noise level is large and that target statistical anisotropy has a blue-tilted shape in Fourier space. The application of the TripoSH-based analysis to forthcoming all-sky survey data could result in constraints on anisotropy comparable to or tighter than the current cosmic microwave background ones.
