REIONIZATION ON LARGE SCALES. I. A PARAMETRIC MODEL CONSTRUCTED FROM RADIATION-HYDRODYNAMIC SIMULATIONS
REIONIZATION ON LARGE SCALES. I. A PARAMETRIC MODEL CONSTRUCTED FROM RADIATION-HYDRODYNAMIC SIMULATIONS
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DOI：
10.1088/0004-637x/776/2/81
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发表时间：
2012-11
期刊：
影响因子：
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通讯作者：
N. Battaglia;H. Trac;R. Cen;A. Loeb
中科院分区：
文献类型：
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作者：
N. Battaglia;H. Trac;R. Cen;A. Loeb
我们提出了一种模拟大尺度非均匀宇宙再电离的新方法。利用在L = 100 Mpc h−1的盒子中对20483个暗物质粒子、20483个气体细胞和170亿个自适应射线进行的高分辨率辐射-流体动力学模拟，我们表明密度和再电离红移场在大尺度（≥1 Mpc h−1）上高度相关。这种相关性在统计上可以用尺度相关的线性偏差来表示。我们构造了偏置的参数函数，然后用它来过滤任意大尺度密度场，从而得到相应的空间变化的再电离红移场。参数化模型有三个自由参数，当我们将两个偏置参数与仿真结果拟合时，可以将其简化为一个自由参数。我们可以通过结合整体电离历史和电离区域之间的相关长度的结果来区分偏置参数的简并组合。与以往的半解析模型不同，我们的模型直接将再电离红移场的演变与模拟进行逐个细胞的比较，并在所有测试中表现良好。我们的模型将高分辨率、中体积的辐射-流体动力学模拟映射到低分辨率、大体积的n-体模拟（约2 Gpc h- 1）上，以便进行模拟观测和理论预测。
We present a new method for modeling inhomogeneous cosmic reionization on large scales. Utilizing high-resolution radiation-hydrodynamic simulations with 20483 dark matter particles, 20483 gas cells, and 17 billion adaptive rays in a L = 100 Mpc h−1 box, we show that the density and reionization redshift fields are highly correlated on large scales (≳ 1 Mpc h−1). This correlation can be statistically represented by a scale-dependent linear bias. We construct a parametric function for the bias, which is then used to filter any large-scale density field to derive the corresponding spatially varying reionization redshift field. The parametric model has three free parameters that can be reduced to one free parameter when we fit the two bias parameters to simulation results. We can differentiate degenerate combinations of the bias parameters by combining results for the global ionization histories and correlation length between ionized regions. Unlike previous semi-analytic models, the evolution of the reionization redshift field in our model is directly compared cell by cell against simulations and performs well in all tests. Our model maps the high-resolution, intermediate-volume radiation-hydrodynamic simulations onto lower-resolution, larger-volume N-body simulations (≳ 2 Gpc h−1) in order to make mock observations and theoretical predictions.