标题： 宇宙-中微子：非线性中微子功率谱的模拟器 显示英文标题

标题： Cosmic-Enu: An emulator for the non-linear neutrino power spectrum

摘要： 宇宙学即将能够测量中微子质量总和$M_\nu$，并且已经确定了几种对中微子敏感的小尺度观测量，这需要在广泛的长度尺度上对中微子聚集进行准确预测。 FlowsForTheMasses 的非线性扰动理论用于大质量中微子功率谱，$\Delta^2_\nu(k)$与它的配套 N-body 模拟在$10\%-15\%$级别上一致，适用于$k \leq 1~h/$Mpc。 在 Mira-Titan IV 冷物质模拟器的基础上，我们使用 FlowsForTheMasses 构建了一个模拟器用于$\Delta^2_\nu(k)$，覆盖了广泛的宇宙学参数和中微子比例$\Omega_{\nu,0} h^2 \leq 0.01$，这对应于$M_\nu \leq 0.93$~eV。 与FlowsForTheMasses在$3.5\%$层级一致，它返回以毫秒为单位的功率谱。 按初始动量对中微子进行排序，我们还模拟了动量十分位的功率谱，提供了关于其扰动分布函数的信息。 将一个$M_\nu=0.15$eV模型与一系列N体模拟方法进行比较，我们发现对于$k \leq 3 k_\mathrm{FS} = 0.17~h/$Mpc的尺度，一致性达到$3\%$，而对于$19\%$Mpc的尺度，一致性达到$k \leq 0.4~h/$。 我们发现增强因子，即$\Delta^2_\nu(k)$与其线性响应对应的比值，与$\Omega_{\nu,0} h^2$最为相关，同时也与聚类振幅$\sigma_8$相关。 此外，非线性效应使自由流限制的标度$\partial \log(\Delta^2_\nu / \Delta^2_{\rm m}) / \partial \log(M_\nu)$超过其线性值 4，增加了小尺度中微子密度对$M_\nu$的敏感性。 显示英文摘要

摘要： Cosmology is poised to measure the neutrino mass sum $M_\nu$ and has identified several smaller-scale observables sensitive to neutrinos, necessitating accurate predictions of neutrino clustering over a wide range of length scales. The FlowsForTheMasses non-linear perturbation theory for the massive neutrino power spectrum, $\Delta^2_\nu(k)$, agrees with its companion N-body simulation at the $10\%-15\%$ level for $k \leq 1~h/$Mpc. Building upon the Mira-Titan IV emulator for the cold matter, we use FlowsForTheMasses to construct an emulator for $\Delta^2_\nu(k)$ covering a large range of cosmological parameters and neutrino fractions $\Omega_{\nu,0} h^2 \leq 0.01$, which corresponds to $M_\nu \leq 0.93$~eV. Consistent with FlowsForTheMasses at the $3.5\%$ level, it returns a power spectrum in milliseconds. Ranking the neutrinos by initial momenta, we also emulate the power spectra of momentum deciles, providing information about their perturbed distribution function. Comparing a $M_\nu=0.15$~eV model to a wide range of N-body simulation methods, we find agreement to $3\%$ for $k \leq 3 k_\mathrm{FS} = 0.17~h/$Mpc and to $19\%$ for $k \leq 0.4~h/$Mpc. We find that the enhancement factor, the ratio of $\Delta^2_\nu(k)$ to its linear-response equivalent, is most strongly correlated with $\Omega_{\nu,0} h^2$, and also with the clustering amplitude $\sigma_8$. Furthermore, non-linearities enhance the free-streaming-limit scaling $\partial \log(\Delta^2_\nu / \Delta^2_{\rm m}) / \partial \log(M_\nu)$ beyond its linear value of 4, increasing the $M_\nu$-sensitivity of the small-scale neutrino density.