Title: Cosmic expansion history from SNe Ia data via information field theory -- the charm code Show Chinese title

Title: 超新星Ia数据的宇宙膨胀历史——信息场论的魅力代码

Abstract: We present charm (cosmic history agnostic reconstruction method), a novel inference algorithm that reconstructs the cosmic expansion history as encoded in the Hubble parameter $H(z)$ from SNe Ia data. The novelty of the approach lies in the usage of information field theory, a statistical field theory that is very well suited for the construction of optimal signal recovery algorithms. The charm algorithm infers non-parametrically $s(a)=\ln(\rho(a)/\rho_{\mathrm{crit}0})$, the density evolution which determines $H(z)$, without assuming an analytical form of $\rho(a)$ but only its smoothness with the scale factor $a=(1+z)^{-1}$. The inference problem of recovering the signal $s(a)$ from the data is formulated in a fully Bayesian way. In detail, we have rewritten the signal as the sum of a background cosmology and a perturbation. This allows us to determine the maximum a posteriory estimate of the signal by an iterative Wiener filter method. Applying charm to the Union2.1 supernova compilation, we have recovered a cosmic expansion history that is fully compatible with the standard $\Lambda$CDM cosmological expansion history with parameter values consistent with the results of the Planck mission. Show Chinese abstract

Abstract: 我们提出了charm（宇宙历史无关重构方法），一种新颖的推理算法，它从Ia型超新星数据中重构了作为哈勃参数$H(z)$编码的宇宙膨胀历史。 该方法的新颖之处在于使用了信息场理论，这是一种非常适合构建最优信号恢复算法的统计场理论。 charm算法非参数地推断$s(a)=\ln(\rho(a)/\rho_{\mathrm{crit}0})$，即决定$H(z)$的密度演化，而不需要假设$\rho(a)$的解析形式，只需假设其与尺度因子$a=(1+z)^{-1}$的光滑性。 从数据中恢复信号$s(a)$的推理问题以完全贝叶斯的方式表述。 具体来说，我们将信号重写为背景宇宙学和扰动的总和。 这使我们能够通过迭代维纳滤波法确定信号的最大后验估计值。 将charm应用于Union2.1超新星编译数据集，我们恢复了一个宇宙膨胀历史，该历史与标准的$\Lambda$CDM宇宙学膨胀历史完全一致，其参数值与Planck任务的结果一致。