Precision cosmology in muddy waters: Cosmological constraints and N-body codes
Precision cosmology in muddy waters: Cosmological constraints and N-body codes
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DOI：
10.1093/mnras/stu272
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发表时间：
2012-11
影响因子：
4.8
通讯作者：
R. Smith;D. Reed;D. Potter;L. Marian;M. Crocce;B. Moore
中科院分区：
文献类型：
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作者：
R. Smith;D. Reed;D. Potter;L. Marian;M. Crocce;B. Moore
未来对宇宙的大尺度结构调查将以前所未有的准确性来约束宇宙学模型和暗能量的真实性质。为了使这些调查达到他们的设计目标，他们将需要对非线性物质功率谱的预测达到百分之一以下的准确度。通过使用一个大的合奏宇宙学N体模拟，我们证明，如果我们不了解与模拟结构形成，即知识的“最佳”模拟参数的不确定性，并简单地寻求边缘化他们，那么这种未来的调查的约束力可以显着降低。然而，对于参数{ns，h，ΩB，Ωm}，这种影响可以通过添加来自宇宙微波背景实验（如普朗克）的信息来大大减轻。相比之下，对于波动幅度σ8和暗能量的时间演化状态方程{w 0，wa}，减轻是温和的。在边缘化的模拟参数，我们发现，暗能量的品质因数可以降低10.2。这可能是一个乐观的评估，因为我们没有考虑其他重要的模拟参数。需要注意的是，我们假设当从我们采用的模拟参数集移动到最佳模拟参数集时，似然函数的Hessian不会发生显著变化。因此，本文提供了强有力的动机，严格的收敛性测试的N体代码，以满足未来的挑战，精密宇宙学。
Future large-scale structure surveys of the Universe will aim to constrain the cosmological model and the true nature of dark energy with unprecedented accuracy. In order for these surveys to achieve their designed goals, they will require predictions for the non-linear matter power spectrum to sub-percent accuracy. Through the use of a large ensemble of cosmological N-body simulations, we demonstrate that if we do not understand the uncertainties associated with simulating structure formation, i.e. knowledge of the `optimal' simulation parameters, and simply seek to marginalize over them, then the constraining power of such future surveys can be significantly reduced. However, for the parameters {ns, h, Ωb, Ωm}, this effect can be largely mitigated by adding the information from a cosmic microwave background experiment, like Planck. In contrast, for the amplitude of fluctuations σ8 and the time-evolving equation of state of dark energy {w0, wa}, the mitigation is mild. On marginalizing over the simulation parameters, we find that the dark-energy figure of merit can be degraded by ˜2. This is likely an optimistic assessment, since we do not take into account other important simulation parameters. A caveat is our assumption that the Hessian of the likelihood function does not vary significantly when moving from our adopted to the optimal simulation parameter set. This paper therefore provides strong motivation for rigorous convergence testing of N-body codes to meet the future challenges of precision cosmology.