arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 0802.1808astro-ph
收藏

重子声学振荡的模拟I:大尺度密度涨落的增长

Simulations of Baryon Acoustic Oscillations I: Growth of Large-Scale Density Fluctuations

Ryuichi Takahashi, Naoki Yoshida, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Takahiro Nishimichi, Akihito Shirata, Atsushi Taruya, Shun Saito, Kazuhiro Yahata, Yasushi Suto

摘要:

我们批判性地研究如何以及大规模的密度扰动的演变是遵循宇宙学$N$体模拟。我们首先运行一个大体积的模拟,并在三维傅立叶空间进行模式的模式分析。我们发现,大规模波动的增长显着偏离线性理论的预测。这些偏差是由{ \it非线性}与最大尺度下的少量模式耦合引起的,这是由于模拟体积有限。然后,我们开发了一个基于二阶微扰理论的分析模型来量化的效果。我们的模型准确地再现了模拟结果。对于一个单一的实现,二阶效应典型地表现为围绕线性理论预测的“之字形”图案,这在真实的重子声学振荡上留下了人为的“振荡”。虽然许多实现的系综平均接近线性理论预测,实现的分散仍然很大,即使是一个大的模拟体积的几百兆秒差距的一面。对于标准的$Λ$ CDM模型,对于具有$L = 500h^{-1}$ Mpc的模拟体积和波数为$Δk = 0.005h$ Mpc $^{-1}$的箱宽,与线性增长率的偏差高达10%,这与高斯随机实现的固有方差相当。我们发现,分散体的规模为$\propto L^{-3/2} Δk^{-1/2}$和平均色散幅度可以小于百分之一,只有当我们使用一个非常大的体积的$L > 2h^{-1}$ Gpc。有限的盒子尺寸效应需要适当地考虑到从大尺度结构模拟的结果,为未来的暗能量调查使用重子声学振荡解释。

英文摘要:

We critically examine how well the evolution of large-scale density perturbations is followed in cosmological $N$-body simulations. We first run a large volume simulation and perform a mode-by-mode analysis in three-dimensional Fourier space. We show that the growth of large-scale fluctuations significantly deviates from linear theory predictions. The deviations are caused by {\it nonlinear} coupling with a small number of modes at largest scales owing to finiteness of the simulation volume. We then develop an analytic model based on second-order perturbation theory to quantify the effect. Our model accurately reproduces the simulation results. For a single realization, the second-order effect appears typically as ``zig-zag'' patterns around the linear-theory prediction, which imprints artificial ``oscillations'' that lie on the real baryon-acoustic oscillations. Although an ensemble average of a number of realizations approaches the linear theory prediction, the dispersions of the realizations remain large even for a large simulation volume of several hundred megaparsecs on a side. For the standard $Λ$CDM model, the deviations from linear growth rate are as large as 10 percent for a simulation volume with $L = 500h^{-1}$Mpc and for a bin width in wavenumber of $Δk = 0.005h$Mpc$^{-1}$, which are comparable to the intrinsic variance of Gaussian random realizations. We find that the dispersions scales as $\propto L^{-3/2} Δk^{-1/2}$ and that the mean dispersion amplitude can be made smaller than a percent only if we use a very large volume of $L > 2h^{-1}$Gpc. The finite box size effect needs to be appropriately taken into account when interpreting results from large-scale structure simulations for future dark energy surveys using baryon acoustic oscillations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑