Coyote宇宙扩展：物质功率谱的精确仿真
The Coyote Universe Extended: Precision Emulation of the Matter Power Spectrum
摘要：
现代巡天观测正在返回宇宙学统计的精确测量结果，如弱透镜剪切相关、星系分布和星系团丰度。为了充分利用这些观测结果，理论家必须提供至少与测量一样准确的预测，以及建模过程中固有的系统误差的可靠估计。在结构形成的非线性领域，这一挑战只能通过发展涵盖一系列宇宙学模型和天体物理过程的大规模多物理场模拟能力来克服。作为实现这一目标的第一步，我们最近开发了一个物质功率谱的预测方案（所谓的仿真器），基于一组高精度的N体模拟，对于wCDM宇宙学，其精度在1%的水平上达到k~1/Mpc和z=1。我们非常希望增加红移和波数的范围，并扩大宇宙学参数空间的范围。为了在这个方向上取得进展，同时最大限度地减少计算成本，我们提出了一种策略，最大限度地重复使用原始模拟。我们证明了原始空间动态范围的一个数量级的改进，达到k~10 h/Mpc，红移覆盖率增加了四倍，z=4，现在包括哈勃参数作为一个新的自变量。为了进一步扩大k和z的范围，将以适度成本运行的一组新的嵌套模拟添加到原始组中。在h中的扩展是通过在用于构建仿真器的多尺度过程内包括微扰理论结果来执行的。这种经济的方法仍然提供了出色的误差控制，约5%的边缘附近的域的仿真器的适用性。新模拟器的公共域代码作为本文所介绍的工作的一部分发布。
英文摘要：
Modern sky surveys are returning precision measurements of cosmological statistics such as weak lensing shear correlations, the distribution of galaxies, and cluster abundance. To fully exploit these observations, theorists must provide predictions that are at least as accurate as the measurements, as well as robust estimates of systematic errors that are inherent to the modeling process. In the nonlinear regime of structure formation, this challenge can only be overcome by developing a large-scale, multi-physics simulation capability covering a range of cosmological models and astrophysical processes. As a first step to achieving this goal, we have recently developed a prediction scheme for the matter power spectrum (a so-called emulator), accurate at the 1% level out to k~1/Mpc and z=1 for wCDM cosmologies based on a set of high-accuracy N-body simulations. It is highly desirable to increase the range in both redshift and wavenumber and to extend the reach in cosmological parameter space. To make progress in this direction, while minimizing computational cost, we present a strategy that maximally re-uses the original simulations. We demonstrate improvement over the original spatial dynamic range by an order of magnitude, reaching k~10 h/Mpc, a four-fold increase in redshift coverage, to z=4, and now include the Hubble parameter as a new independent variable. To further the range in k and z, a new set of nested simulations run at modest cost is added to the original set. The extension in h is performed by including perturbation theory results within a multi-scale procedure for building the emulator. This economical methodology still gives excellent error control, ~5% near the edges of the domain of applicability of the emulator. A public domain code for the new emulator is released as part of the work presented in this paper.
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