论文标题
宇宙黎明III中Z = 6处的短电离光子平均自由路径，这是一种新的全偶联辐射流动力学模拟，对电离时代的时代
The short ionizing photon mean free path at z=6 in Cosmic Dawn III, a new fully-coupled radiation-hydrodynamical simulation of the Epoch of Reionization
论文作者
论文摘要
在$ \ rm z = 6 $下的电离光子（MFP）平均自由路径（MFP）的最新确定低于许多理论预测。为了深入了解这个问题，我们研究了MFP在我们新的全面完全耦合的辐射流体动力学宇宙学模拟中的演变：Cosmic Dawn III（Codaiii）。 Codaiii的规模（$ \ rm 94^3 \，cmpc^3 $）和分辨率（$ \ rm 8192^3 $ grid）使其特别适合在恢复过程中研究IgM的演变。该模拟是用summit上的Ramses-Cudaton进行的，并使用了131072处理器，耦合到24576 GPU，使其成为最大的电源模拟，并进行了有史以来最大的Ramses模拟。在Codaiii中，与Codaii相比，与全球限制的限制相比，尤其是对于中性氢分子的演变和宇宙光电离心速率，由于校准的改善，均一回报（$ \ rm z = 5.6 $），以及更高的空间分辨率。分析MFP时，我们发现Codaiii重现了最新的观察结果，从$ \ rm z = 6 $到$ \ rm z = 4.6 $。我们表明，由于电离的斑块和在re次离子过程中中性与电离区域的共存，MFP在Codaiii中的分布分别具有短（中性）和长（电离）MFP模式。中性模式在Sub-kpc处峰值至MFP的KPC量表，而电离模式峰值从$ \ rm 0.1 mpc/h $ th $ \ rm z = 7 $至$ \ sim 10 $ \ sim 10 $ mpc/h以$ \ rm z = 5.2 $进化。将MFP计算为电离模式的平均值，为最近的观测确定提供了最佳匹配。分布在$ \ rm z> 13 $（$ \ rm z <5 $）下减少到单个中性（电离）模式。
Recent determinations of the mean free path of ionising photons (mfp) in the intergalactic medium (IGM) at $\rm z=6$ are lower than many theoretical predictions. To gain insight into this issue, we investigate the evolution of the mfp in our new massive fully coupled radiation hydrodynamics cosmological simulation of reionization: Cosmic Dawn III (CoDaIII). CoDaIII's scale ($\rm 94^3 \, cMpc^3$) and resolution ($\rm 8192^3$ grid) make it particularly suitable to study the evolution of the IGM during Reionization. The simulation was performed with RAMSES-CUDATON on Summit, and used 131072 processors coupled to 24576 GPUs, making it the largest Reionization simulation, and largest RAMSES simulation ever performed. A superior agreement with global constraints on Reionization is obtained in CoDaIII over CoDaII especially for the evolution of the neutral hydrogen fraction and the cosmic photo-ionization rate, thanks to an improved calibration, later end of reionization ($\rm z=5.6$), and higher spatial resolution. Analyzing the mfp, we find that CoDaIII reproduces the most recent observations very well, from $\rm z=6$ to $\rm z=4.6$. We show that the distribution of the mfp in CoDaIII is bimodal, with short (neutral) and long (ionized) mfp modes, respectively, due to the patchiness of reionization and the co-existence of neutral versus ionized regions during Reionization. The neutral mode peaks at sub-kpc to kpc scales of mfp, while the ionized mode peak evolves from $\rm 0.1 Mpc/h$ at $\rm z=7$ to $\sim 10$ Mpc/h at $\rm z=5.2$. Computing the mfp as the average of the ionized mode provides the best match to the recent observational determinations. The distribution reduces to a single neutral (ionized) mode at $\rm z>13$ ($\rm z<5$).
