The Bispectrum as a Signature of Gravitational Instability in Redshift Space
The Bispectrum as a Signature of Gravitational Instability in Redshift Space
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DOI：
10.1086/307220
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发表时间：
1998-08
期刊：
影响因子：
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通讯作者：
R. Scoccimarro;H. Couchman;J. Frieman
中科院分区：
文献类型：
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作者：
R. Scoccimarro;H. Couchman;J. Frieman
双谱提供了引力不稳定性的特征信号，可以用来探测初始条件的高斯性和星系分布的偏差。我们利用微扰理论和高分辨率数值模拟研究了红移扭曲对这一特征的影响。我们得到了红移空间双谱的多极展开的微扰结果，这为打破红移空间功率谱测量中存在的偏差和Ω之间的简并提供了一种自然的方法。我们提出了一个包含微扰结果的唯象模型，并描述了在向非线性区域的转变中的双谱。我们强调了非线性效应的重要性，并表明对这些效应的不准确处理可能会导致从星系红移调查中确定偏差的显著差异。在小尺度上，我们发现双谱单极子表现出强烈的组态依赖性，反映了团簇的速度色散。因此，三点函数的层次模型在红移空间中不成立。
The bispectrum provides a characteristic signature of gravitational instability that can be used to probe the Gaussianity of the initial conditions and the bias of the galaxy distribution. We study how this signature is affected by redshift distortions using perturbation theory and high-resolution numerical simulations. We obtain perturbative results for the multipole expansion of the redshift-space bispectrum that provide a natural way to break the degeneracy between bias and Ω present in measurements of the redshift-space power spectrum. We propose a phenomenological model that incorporates the perturbative results and also describes the bispectrum in the transition to the nonlinear regime. We stress the importance of nonlinear effects and show that inaccurate treatment of these can lead to significant discrepancies in the determination of bias from galaxy redshift surveys. At small scales we find that the bispectrum monopole exhibits a strong configuration dependence that reflects the velocity dispersion of clusters. Therefore the hierarchical model for the three-point function does not hold in redshift space.