用神经网络精准模拟多种宇宙模型下的物质功率谱,精度达亚百分之一。
Dark Quest II: A Wide-Coverage Neural Network Emulator of the Nonlinear Matter Power Spectrum Across Extended Cosmologies

- 输入融合宇宙参数与物理辅助量,提升跨参数空间泛化能力
- 在1Gpc盒、3000³粒子下,10 h/Mpc以内误差小于1%
- 支持高分辨率与低分辨率模拟协同训练,适合大规模宇宙学研究
DarkEmulator2 是一个针对九维 $w_0 w_a νo \mathrm{CDM}$ 宇宙学参数空间的非线性物质功率谱神经网络模拟器,作为 Dark Quest II (DQ2) 项目的核心组件。其训练数据基于 extsc{Ginkaku} 代码生成的模拟,该代码的数值实现、精度测试与后处理流程已在配套论文中详述。模型设计采用统一策略:除宇宙学参数向量外,还引入三类物理解释性辅助输入——线性物质功率谱、模拟分辨率描述符,以及初始高斯随机场的低维摘要,以增强参数空间泛化能力。通过联合训练三个不同分辨率层级的模拟数据,仅需少量高分辨率模拟即可实现广泛覆盖。对于 $L_{\mathrm{box}}=1\,\hiGpc$、$N=3000^{3}$ 粒子的模拟盒,该模拟器在 $k_{\mathrm{Ny}}\simeq 10\,\hMpci$ 的粒子奈奎斯特频率内,对物质功率谱的重现精度达到亚百分之一。在标定波数范围内保持高精度,最高 $k$ 值预测受模拟分辨率和粒子噪声影响。通过独立测试集验证,并与多个公开模拟器及常用拟合公式对比,量化了模型间一致性及残差的参数依赖趋势。
原文摘要 · Abstract (English)
\textsc{DarkEmulator2} is a neural network emulator of the nonlinear matter power spectrum in a nine-dimensional $w_0 w_a νo \mathrm{CDM}$ parameter space, developed as the emulator component of the \textsc{Dark Quest II} (DQ2) program. It is trained on simulations generated with the \textsc{Ginkaku} code, whose numerical implementation, accuracy tests, and post-processing pipeline are described in the companion paper. The design follows a unified strategy: in addition to the cosmological parameter vector, we supplement the neural network's inputs with three families of physically motivated auxiliary quantities -- the linear matter power spectrum, descriptors of the simulation resolution, and a low-dimensional summary of the initial Gaussian random field -- that are expected to improve generalization across the parameter space. Training a single network jointly across three simulation resolution tiers allows the emulator to exploit a small number of high-resolution simulations while retaining broad coverage from lower-resolution simulations. For a $L_{\mathrm{box}}=1\,\hiGpc$ box with $N=3000^{3}$ particles, the emulator reproduces the simulated matter power spectrum to subpercent accuracy up to the particle Nyquist scale, $k_{\mathrm{Ny}}\simeq 10\,\hMpci$. The emulator remains accurate over the calibrated wavenumber range, while its highest-$k$ predictions depend on the simulation resolution and shot noise. We validate the emulator on independent test suites and, through a cross-comparison with several public emulators and widely used fitting formulas, characterize the inter-model consistency and the parameter-dependent trends in their residuals.
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