不同数据集下暗能量状态方程的非参数重建
Nonparametric Reconstruction of the Dark Energy Equation of State from Diverse Data Sets
摘要：
宇宙加速膨胀的原因是当今物理学中最基本的问题之一。在缺乏一个令人信服的理论来解释观测结果的情况下，首要任务是发展一个强大的现象学。如果加速是由某种形式的暗能量驱动的，那么，这种现象是由暗能量状态方程w决定的。正在进行的和即将进行的宇宙学调查的一个主要目标是测量W及其时间依赖性的高精度。由于w（z）不能直接测量，因此需要强大的重建方法来从观测中可靠地提取它。最近，我们介绍了一种新的重建方法的基础上高斯过程建模的w（z）。该方法可以捕获w（z）中的非平凡时间依赖性，最重要的是，它可以产生受控和无偏的误差估计。在本文中，我们扩展的方法，包括一组不同的测量：重子声学振荡，宇宙微波背景测量，和超新星的数据。我们分析了目前可用的数据集，并提出了由此产生的约束w（z），发现目前的观测结果是非常好的协议与宇宙学常数。此外，我们探讨如何以及我们的方法捕捉w（z）的非平凡行为，通过分析模拟数据，假设高质量的观察，从未来的调查。我们发现，重子声学振荡测量本身已经导致非常好的重建结果，不同的高质量探针的组合，使我们能够非常可靠地重建w（z）与小的误差范围。
英文摘要：
The cause of the accelerated expansion of the Universe poses one of the most fundamental questions in physics today. In the absence of a compelling theory to explain the observations, a first task is to develop a robust phenomenology. If the acceleration is driven by some form of dark energy, then, the phenomenology is determined by the dark energy equation of state w. A major aim of ongoing and upcoming cosmological surveys is to measure w and its time dependence at high accuracy. Since w(z) is not directly accessible to measurement, powerful reconstruction methods are needed to extract it reliably from observations. We have recently introduced a new reconstruction method for w(z) based on Gaussian process modeling. This method can capture nontrivial time-dependences in w(z) and, most importantly, it yields controlled and unbaised error estimates. In this paper we extend the method to include a diverse set of measurements: baryon acoustic oscillations, cosmic microwave background measurements, and supernova data. We analyze currently available data sets and present the resulting constraints on w(z), finding that current observations are in very good agreement with a cosmological constant. In addition we explore how well our method captures nontrivial behavior of w(z) by analyzing simulated data assuming high-quality observations from future surveys. We find that the baryon acoustic oscillation measurements by themselves already lead to remarkably good reconstruction results and that the combination of different high-quality probes allows us to reconstruct w(z) very reliably with small error bounds.
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