Arico' Giovanni, Angulo Raul, Zennaro Matteo
Donostia International Physics Center, Donostia/San Sebastián, Gipuzkoa, 20018, Spain.
Departamento de Física, Universidad de Zaragoza, Zaragoza, Aragon, 50009, Spain.
Open Res Eur. 2022 Jun 15;1:152. doi: 10.12688/openreseurope.14310.2. eCollection 2021.
The linear matter power spectrum is an essential ingredient in all theoretical models for interpreting large-scale-structure observables. Although Boltzmann codes such as CLASS or CAMB are very efficient at computing the linear spectrum, the analysis of data usually requires 10 -10 evaluations, which means this task can be the most computationally expensive aspect of data analysis. Here, we address this problem by building a neural network emulator that provides the linear theory (total and cold) matter power spectrum in about one millisecond with ≈0.2%(0.5%) accuracy over redshifts z ≤ 3 (z ≤ 9), and scales10 ≤ k [ Mpc ] < 50. We train this emulator with more than 200,000 measurements, spanning a broad cosmological parameter space that includes massive neutrinos and dynamical dark energy. We show that the parameter range and accuracy of our emulator is enough to get unbiased cosmological constraints in the analysis of a Euclid-like weak lensing survey. Complementing this emulator, we train 15 other emulators for the cross-spectra of various linear fields in Eulerian space, as predicted by 2nd-order Lagrangian Perturbation theory, which can be used to accelerate perturbative bias descriptions of galaxy clustering. Our emulators are specially designed to be used in combination with emulators for the nonlinear matter power spectrum and for baryonic effects, all of which are publicly available at http://www.dipc.org/bacco.
线性物质功率谱是所有用于解释大尺度结构可观测量的理论模型中的一个重要组成部分。尽管诸如CLASS或CAMB之类的玻尔兹曼代码在计算线性谱方面非常高效，但数据分析通常需要进行10 - 10次评估，这意味着这项任务可能是数据分析中计算成本最高的方面。在这里，我们通过构建一个神经网络模拟器来解决这个问题，该模拟器能在大约一毫秒内提供线性理论（总物质和冷物质）功率谱，在红移z ≤ 3（z ≤ 9）以及尺度10 ≤ k [Mpc] < 50的范围内，精度约为0.2%（0.5%）。我们用超过200,000次测量对这个模拟器进行训练，测量数据跨越了一个广泛的宇宙学参数空间，其中包括大质量中微子和动态暗能量。我们表明，我们模拟器的参数范围和精度足以在类似欧几里得的弱引力透镜调查分析中获得无偏的宇宙学约束。作为对这个模拟器的补充，我们针对欧拉空间中各种线性场的交叉谱训练了另外15个模拟器，这些交叉谱由二阶拉格朗日微扰理论预测，可用于加速星系团聚类的微扰偏差描述。我们的模拟器经过专门设计，可与用于非线性物质功率谱和重子效应的模拟器结合使用，所有这些模拟器均可在http://www.dipc.org/bacco上公开获取。
