标题： 第一十亿年中的秒：一种包含第三星族的21厘米信号有效模型 显示英文标题

标题： The First Billion Years in Seconds: An Effective Model for the 21-cm Signal with Population III Stars

摘要： 观测21厘米信号正在打开一扇观察宇宙黎明时期的窗口，那时第一颗恒星形成了。 这些观测通常通过半数值或流体动力学模拟来解释，这些模拟通常计算量大且对宇宙学或天体物理效应的变化不够灵活。 在这里，我们提出了一种有效且完全解析的模型，用于描述第一颗恒星对21厘米信号的影响，使用了模块化代码Zeus21。 Zeus21采用解析的恒星形成率密度（SFRD）方案，以恢复决定21厘米信号的完全非线性和非局部辐射场的相关性。 我们在Zeus21中引入了最早存在于低质量分子冷却星系中的第三代恒星（Pop III），它们的光谱与后来的Pop II恒星不同。 我们还自洽地模拟了反馈形式的$H_2$-解离的莱曼-沃泽（LW）辐射，以及暗物质-重子相对速度，这两种因素都会抑制最低质量晕中的恒星形成。 LW反馈由于LW光子的长平均自由路径而在SFRD波动中产生尺度依赖性。 相对速度导致21厘米信号的空间分布出现“波动”；我们提出了对这些速度引起的声学振荡形状的改进计算，表明它们在宇宙黎明时期仍然是标准的标尺。 我们改进后的Zeus21版本预测的21厘米全局信号和功率谱与模拟结果在$\sim 10\%$级别上一致，但速度至少快三个数量级。 这个公开代码代表了在宇宙黎明时期实现高效和灵活参数推断的一个步骤，使我们能够在几秒钟内预测宇宙的前十亿年。 显示英文摘要

摘要： Observations of the 21-cm signal are opening a window to the cosmic-dawn epoch, when the first stars formed. These observations are usually interpreted with semi-numerical or hydrodynamical simulations, which are often computationally intensive and inflexible to changes in cosmological or astrophysical effects. Here, we present an effective, fully analytic model for the impact of the first stars on the 21-cm signal, using the modular code Zeus21. Zeus21 employs an analytic prescription of the star formation rate density (SFRD) to recover the fully nonlinear and nonlocal correlations of radiative fields that determine the 21-cm signal. We introduce the earliest Population III (Pop III) stars residing in low-mass molecular-cooling galaxies in Zeus21, with distinct spectra from later Pop II stars. We also self-consistently model feedback in the form of $H_2$-dissociating Lyman-Werner (LW) radiation, as well as dark matter-baryon relative velocities, both of which suppress star formation in the lowest-mass halos. LW feedback produces a scale-dependence on the SFRD fluctuations, due to the long mean free path of LW photons. Relative velocities give rise to "wiggles" in the spatial distribution of the 21-cm signal; we present an improved calculation of the shape of these velocity-induced acoustic oscillations, showing they remain a standard ruler at cosmic dawn. Our improved version of Zeus21 predicts the 21-cm global signal and power spectra in agreement with simulations at the $\sim 10\%$ level, yet is at least three orders of magnitude faster. This public code represents a step towards efficient and flexible parameter inference at cosmic dawn, allowing us to predict the first billion years of the universe in mere seconds.