Direct and fast calculation of regularized cosmological power spectrum at two-loop order
Direct and fast calculation of regularized cosmological power spectrum at two-loop order
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DOI：
10.1103/physrevd.86.103528
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发表时间：
2012-08
影响因子：
5
通讯作者：
A. Taruya;F. Bernardeau;T. Nishimichi;S. Codis
中科院分区：
文献类型：
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作者：
A. Taruya;F. Bernardeau;T. Nishimichi;S. Codis
我们提出了一个具体的处方宇宙学功率谱的计算，利用这里在两个循环的顺序微扰论，基于多点传播子展开。在这种方法中，密度和速度的功率谱构造从正则表达式的传播，再现在高$k$限制和标准微扰理论的结果在低$k$的行为。借助$N$体模拟，我们特别关注的密度场，并表明，这样的建设提供了强大的和准确的预测的密度功率谱和相关函数在百分比水平的弱非线性制度。然后，我们提出了一个算法，允许加速评估所有需要的图，减少计算任务的一维积分。这是通过为适当选择的基准模型定义的预先计算的内核集来实现的。两个循环结果的计算时间从直接法的几分钟减少到快速法的几秒钟。该方法的鲁棒性和适用性进行了测试对功率谱宇宙模拟器，从各种各样的宇宙学模型可以探索。可以直接和快速计算密度功率谱的Fortran程序，RegPT，作为本文的一部分公开发布。
We present a specific prescription for the calculation of cosmological power spectra, exploited here at two-loop order in perturbation theory, based on the multipoint propagator expansion. In this approach, density and velocity power spectra are constructed from the regularized expressions of the propagators that reproduce both the resummed behavior in the high-$k$ limit and the standard perturbation theory results at low $k$. With the help of $N$-body simulations, we particularly focus on the density field, and show that such a construction gives robust and accurate predictions for both the density power spectrum and the correlation function at percent level in the weakly nonlinear regime. We then present an algorithm that allows accelerated evaluations of all the required diagrams by reducing the computational tasks to one-dimensional integrals. This is achieved by means of precomputed kernel sets defined for appropriately chosen fiducial models. The computational time for two-loop results is then reduced from a few minutes, with the direct method, to a few seconds with the fast one. The robustness and applicability of this method are tested against the power spectrum cosmic emulator from which a wide variety of cosmological models can be explored. The Fortran program with which direct and fast calculations of density power spectra can be done, RegPT, is publicly released as part of this paper.