Flowing with time: a new approach to non-linear cosmological perturbations
Flowing with time: a new approach to non-linear cosmological perturbations
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DOI：
10.1088/1475-7516/2008/10/036
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发表时间：
2008-06
影响因子：
6.4
通讯作者：
M. Pietroni
中科院分区：
文献类型：
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作者：
M. Pietroni
非线性效应对于计算宇宙物质功率谱以达到未来一代调查所需的精度至关重要。本文提出了一种新的方法，即通过对微分方程系统进行积分，在任何红移和任何动量尺度下获得功率谱、双谱和高阶相关。该方法类似于我们熟悉的BBGKY （Bogoliubov-Born-Green-Kirkwood-Yvon）层次结构。在三谱的水平上截断，方程组的解对应于无穷类微扰修正的和。与其他恢复框架相比，这里讨论的方案特别适合于ΛCDM （CDM：冷暗物质）以外的宇宙学，例如基于引力修正和包含大质量中微子的宇宙学。作为第一个应用，我们计算了功率谱的重子声学振荡特征，并将结果与微扰理论、晕模型和n体模拟进行了比较。计算了密度-速度功率谱和速度-速度功率谱，发现它们比密度-密度功率谱受非线性的影响要小得多。这种方法可以看作是重整化群的一种特殊形式，其中时间是流动参数。
Non-linear effects are crucial for computing the cosmological matter power spectrum to the accuracy required by future generation surveys. Here, a new approach is presented, in which the power spectrum, the bispectrum and higher order correlations are obtained—at any redshift and for any momentum scale—by integrating a system of differential equations. The method is similar to that of the familiar BBGKY (Bogoliubov–Born–Green–Kirkwood–Yvon) hierarchy. Truncating at the level of the trispectrum, the solution of the equations corresponds to the summation of an infinite class of perturbative corrections. Compared to other resummation frameworks, the scheme discussed here is particularly suited to cosmologies other than ΛCDM (CDM: cold dark matter), such as those based on modifications of gravity and those containing massive neutrinos. As a first application, we compute the baryonic acoustic oscillation feature of the power spectrum, and compare the results with perturbation theory, the halo model, and N-body simulations. The density–velocity and velocity–velocity power spectra are also computed, revealing that they are much less contaminated by non-linearities than the density–density one. The approach can be seen as a particular formulation of the renormalization group, in which time is the flow parameter.