The pairwise velocity probability density function in models with local primordial non-Gaussianity
The pairwise velocity probability density function in models with local primordial non-Gaussianity
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DOI：
10.1111/j.1365-2966.2011.18390.x
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发表时间：
2010-08
影响因子：
4.8
通讯作者：
T. Lam;T. Nishimichi;N. Yoshida
中科院分区：
文献类型：
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作者：
T. Lam;T. Nishimichi;N. Yoshida
我们利用解析模型和宇宙n体模拟研究了原始非高斯性如何影响成对速度概率密度函数（PDF）。我们采用fnl特征的局部非高斯模型，检验了线性速度差PDF和线性成对速度PDF。我们明确地展示了fnl如何在平行和垂直于分离方向线的原始独立速度之间诱导相关性。我们将模型结果与非高斯模型的n体模拟结果进行了比较。线性理论无法预测fnl模型中的PDF。因此，我们建立了一个基于Zeldovich近似的解析模型来描述速度PDF的演变。我们的分析模型和仿真结果表明，在平行方向和垂直方向上，PDF剖面以及由于原始非高斯性而引起的PDF变化具有非常好的一致性。该协议特别适用于相对较小的分离（<10 h−1 Mpc）。包含速度PDF的演化对于较好地描述PDF中的原始非高斯性特征具有重要意义。我们的模型为在未来的勘探中使用特殊速度约束fnl提供了基础。
We study how primordial non-Gaussianity affects the pairwise velocity probability density function (PDF) using an analytical model and cosmological N-body simulations. We adopt the local type non-Gaussian models characterized by fnl, and examine both the linear velocity difference PDF and the linear pairwise velocity PDF. We show explicitly how fnl induces correlations between originally independent velocities along the parallel and the perpendicular to the line of separation directions. We compare the model results with measurements from N-body simulations of the non-Gaussian models. Linear theory fails to predict the PDF in the fnl models. Therefore, we develop an analytic model based on the Zeldovich approximation to describe the evolution of the velocity PDF. Our analytical model and simulation results show remarkably good agreement in both the parallel and the perpendicular directions for the PDF profiles, as well as the change in the PDF due to primordial non-Gaussianity. The agreement is particularly good for relatively small separations (<10 h−1 Mpc). The inclusion of the evolution of the velocity PDF is important to obtain a good description on the signature of primordial non-Gaussianity in the PDF. Our model provides the foundation to constrain fnl using the peculiar velocity in future surveys.