论文标题
红移空间星系双光谱的模态压缩
Modal compression of the redshift-space galaxy bispectrum
论文作者
论文摘要
我们将模态分解方法扩展到以前应用于将真实空间双光谱中的信息压缩到各向异性红移空间biseptrum。在模态方法方法中，双光谱及其方向的平滑函数扩展，以便一组模态扩展系数可以捕获Bispectrum中的信息。我们假设对压缩模态双光谱的参考调查和计算Fisher的预测，以及在文献中红移空间双光谱的其他两个基础分解，一个基于（单个）球形谐波，另一个基于Tripall spher spher spher spherical谐波。在每种情况下，我们将压缩统计量的预测约束与包括所有三角形和方向的完整，未压缩的双光谱的预测约束进行比较。我们的主要结果是，所有三种压缩方法都可以很好地恢复双光谱的完整信息含量，但是模态分解方法最有效地实现了这一点：只有14（42）个模态膨胀系数才能获得整个Bispectrum结果的10％（2％）以内的约束。下一个最有效的分解是基于三极球谐波的分解，而球形谐波多物的效率最低。
We extend the modal decomposition method, previously applied to compress the information in the real-space bispectrum, to the anisotropic redshift-space galaxy bispectrum. In the modal method approach, the bispectrum is expanded on a basis of smooth functions of triangles and their orientations, such that a set of modal expansion coefficients can capture the information in the bispectrum. We assume a reference survey and compute Fisher forecasts for the compressed modal bispectrum and two other basis decompositions of the redshift-space bispectrum in the literature, one based on (single) spherical harmonics and another based on tripolar spherical harmonics. In each case, we compare the forecasted constraints from the compressed statistic with forecasted constraints from the full, uncompressed bispectrum which includes all triangles and orientations. Our main result is that all three compression methods achieve good recovery of the full information content of the bispectrum, but the modal decomposition approach achieves this the most efficiently: only 14 (42) modal expansion coefficients are necessary to obtain constraints that are within 10% (2%) of the full bispectrum result. The next most efficient decomposition is the one based on tripolar spherical harmonics, while the spherical harmonic multipoles are the least efficient.
