arXiv 2304.033582023-04astro-ph.COastro-ph.GA

微暗晕中第三星族恒星形成的自洽半解析模型

A self-consistent semi-analytic model for Population III star formation in minihalos

Sahil Hegde, Steven R. Furlanetto

备注：: 19 pages, 14 figures, published in MNRAS
DOI：: 10.1093/mnras/stad2308

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本文构建自洽半解析模型，研究微暗晕中Pop III恒星形成，考虑紫外背景、暗物质-重子相对速度和X射线背景的抑制效应，追踪z=50至z=6的恒星形成历史，并识别21厘米信号中的特征。

摘要：

第一代恒星的形成标志着宇宙历史上的一个分水岭时刻。作为首批发光结构，这些恒星（也称为第三星族恒星，或Pop III恒星）孕育了第一批星系，并开启了再电离过程。我们构建了一个解析模型，用以自洽地追踪在波动的紫外背景、早期宇宙遗留的暗物质-重子相对速度以及X射线背景存在下，微暗晕内部第三星族恒星的形成；这些因素在很大程度上抑制了气体的冷却，并延迟了这第一代恒星的形成。我们在一个早期恒星形成的半解析模型中展示了该框架的实用性，该模型还追踪了这些暗晕内Pop III向Pop II恒星形成的转变。利用我们关于允许Pop III恒星形成条件的新方案，我们追踪了从$z=50$到$z=6$的暗物质晕群体，并考察了全球恒星形成历史，发现每个过程都定义了其自身的关键时期：（i）流速度在最高红移（$z\gtrsim30$）时占主导，（ii）紫外背景在中间时期（$30\gtrsim z\gtrsim15$）定下基调，（iii）X射线在最近时期（$z\lesssim 15$）控制Pop III恒星形成的终结。在我们所有的模型中，Pop III恒星持续形成至$z\sim 7-10$，届时它们的超新星可能被即将到来的仪器观测到。最后，我们识别了Pop III物理变化在原子氢的全球21厘米自旋翻转信号中的特征。

英文摘要：

The formation of the first stars marks a watershed moment in the history of our universe. As the first luminous structures, these stars (also known as Population III, or Pop III stars) seed the first galaxies and begin the process of reionization. We construct an analytic model to self-consistently trace the formation of Pop III stars inside minihalos in the presence of the fluctuating ultraviolet background, relic dark matter-baryon relative velocities from the early universe, and an X-ray background, which largely work to suppress cooling of gas and delay the formation of this first generation of stars. We demonstrate the utility of this framework in a semi-analytic model for early star formation that also follows the transition between Pop III and Pop II star formation inside these halos. Using our new prescription for the criteria allowing Pop III star formation, we follow a population of dark matter halos from $z=50$ through $z=6$ and examine the global star formation history, finding that each process defines its own key epoch: (i) the stream velocity dominates at the highest redshifts ($z\gtrsim30$), (ii) the UV background sets the tone at intermediate times ($30\gtrsim z\gtrsim15$), and (iii) X-rays control the end of Pop III star formation at the latest times ($z\lesssim 15$). In all of our models, Pop III stars continue to form down to $z\sim 7-10$, when their supernovae will be potentially observable with forthcoming instruments. Finally, we identify the signatures of variations in the Pop III physics in the global 21-cm spin-flip signal of atomic hydrogen.

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