Recent years have witnessed rapid progress in observations of the Epoch of Reionization (EoR). These have enabled high-dimensional inference of galaxy and intergalactic medium (IGM) properties during the first billion years of our Universe. However, even using efficient, semi-numerical simulations, traditional inference approaches that compute 3D lightcones on-the-fly can take $10^5$ core hours. Here we present 21cmEMU: an emulator of several summary observables from the popular 21cmFAST simulation code. 21cmEMU takes as input nine parameters characterizing EoR galaxies, and outputs the following summary statistics: (i) the IGM mean neutral fraction; (ii) the 21-cm power spectrum; (iii) the mean 21-cm spin temperature; (iv) the sky-averaged (global) 21-cm signal; (vi) the ultraviolet (UV) luminosity functions (LFs); and (vii) the Thomson scattering optical depth to the cosmic microwave background (CMB). All observables are predicted with sub-percent median accuracy, with a reduction of the computational cost by a factor of over 10$^4$. After validating inference results, we showcase a few applications, including: (i) quantifying the relative constraining power of different observational datasets; (ii) seeing how recent claims of a late EoR impact previous inferences; and (iii) forecasting upcoming constraints from the sixth observing season of the Hydrogen Epoch of Reionization Array (HERA) telescope. 21cmEMU is publicly-available, and is included as an alternative simulator in the public 21CMMC sampler.

翻译：近年来，宇宙再电离时期（EoR）的观测研究取得了快速进展。这些进展使得我们能够对宇宙最初十亿年间星系及星系际介质（IGM）的特性进行高维推断。然而，即使采用高效的半数值模拟，传统推断方法需要实时计算三维光锥，其计算成本仍高达 $10^5$ 核心小时。本文介绍 21cmEMU：一个针对流行模拟代码 21cmFAST 中若干摘要观测量的仿真器。21cmEMU 以表征 EoR 星系的九个参数作为输入，输出以下摘要统计量：（i）IGM 平均中性氢比例；（ii）21 厘米功率谱；（iii）平均 21 厘米自旋温度；（iv）天区平均（全局）21 厘米信号；（vi）紫外（UV）光度函数；（vii）宇宙微波背景（CMB）的汤姆逊散射光学深度。所有观测量的预测中值精度优于百分之一，同时计算成本降低了超过 $10^4$ 倍。在验证推断结果后，我们展示了若干应用实例，包括：（i）量化不同观测数据集的相对约束能力；（ii）探究近期关于晚期再电离的论断如何影响先前的推断；（iii）预测氢再电离时期阵列（HERA）望远镜第六观测季即将获得的约束条件。21cmEMU 已公开发布，并作为备选模拟器集成在公开的 21CMMC 采样器中。