Title: On the use of semi-numerical simulations in predicting the 21-cm signal from the epoch of reionization Show Chinese title

Title: 关于使用半数值模拟预测再电离时代的21厘米信号

Abstract: We present a detailed comparison of three different simulations of the epoch of reionization (EoR). The radiative transfer simulation (${\rm C}^2$-RAY) among them is our benchmark. Radiative transfer codes can produce realistic results, but are computationally expensive. We compare it with two semi-numerical techniques: one using the same halos as ${\rm C}^2$-RAY as its sources (Sem-Num), and one using a conditional Press-Schechter scheme (CPS+GS). These are vastly more computationally efficient than ${\rm C}^2$-RAY, but use more simplistic physical assumptions. We evaluate these simulations in terms of their ability to reproduce the history and morphology of reionization. We find that both Sem-Num and CPS+GS can produce an ionization history and morphology that is very close to ${\rm C}^2$-RAY, with Sem-Num performing slightly better compared to CPS+GS. We also study different redshift space observables of the 21-cm signal from EoR: the variance, power spectrum and its various angular multipole moments. We find that both semi-numerical models perform reasonably well in predicting these observables at length scales relevant for present and future experiments. However, Sem-Num performs slightly better than CPS+GS in producing the reionization history, which is necessary for interpreting the future observations. Show Chinese abstract

Abstract: 我们详细比较了三个不同再电离（EoR）时期的模拟。其中辐射传输模拟（${\rm C}^2$-RAY）是我们的基准。辐射传输代码可以产生现实的结果，但计算成本高昂。我们将它与两种半数值技术进行比较：一种使用与${\rm C}^2$-RAY相同的暗晕作为源（Sem-Num），另一种使用条件Press-Schechter方案（CPS+GS）。这些方法比${\rm C}^2$-RAY在计算上高效得多，但采用更简单的物理假设。我们根据它们再现再电离历史和形态的能力来评估这些模拟。我们发现Sem-Num和CPS+GS都能产生非常接近${\rm C}^2$-RAY的电离历史和形态，且Sem-Num的表现略优于CPS+GS。我们还研究了来自EoR的21厘米信号的不同红移空间可观测量：方差、功率谱及其各种角多极矩。我们发现这两种半数值模型在预测当前和未来实验相关尺度上的这些可观测量时表现合理。然而，在产生再电离历史方面，Sem-Num略优于CPS+GS，这对于解释未来的观测至关重要。