A New Generation of Absorption Spectroscopy Experiments Probing the Epoch of Reionization

在早期的宇宙中，星系之间的气体大部分是中性氢。早期的恒星、星系和黑洞发出的辐射电离了这种气体。发生这种情况的时期被称为再电离时期。再电离的历史揭示了早期宇宙的性质和演化。这个项目将利用对最遥远的类星体的观测来研究我们和类星体之间氢气的电离状态。该项目还将研究第一批恒星产生的重元素对气体的富集。该项目还将资助一名研究生，部分资助一名博士后，并在第一年和第二年为西班牙裔服务机构的两名本科生提供暑期津贴。该项目还将为维护和分发用于光谱数据缩减的PypeIt软件包提供间接支持。该项目将利用凯克望远镜200个类星体的光谱数据来研究星系间介质（IGM）。类星体的红移都大于6。光谱分析将允许识别IGM的局部电离状态，以及识别来自第一颗超新星的金属富集IGM的证据。通过确定类星体周围的局部电离状态，该项目还将提供类星体的辐射历史，从而更好地理解这些超大质量黑洞是如何在大爆炸后800迈内成长为如此大的质量的。该项目将进行端到端的分析，包括观测、理论建模、最先进的模拟和贝叶斯推断，为再电离时代的研究提供坚实的方法论基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In the early universe, much of the gas between galaxies was neutral hydrogen. The early generations of stars, galaxies, and black holes emitted radiation that ionized this gas. The period of time when this occurred is known as the epoch of reionization. The history of reionization sheds light on the nature and evolution of the early universe. This project will use observations of the most distant quasars to study the ionization state of the hydrogen gas between us and the quasars. The project will also study the enrichment of the gas by heavier elements produced in the first stars. The project will also support one graduate student, partially support a post-doc, and provide summer stipends for two undergraduates from Hispanic Serving Institutions in years 1 and 2. The project will also provide indirect support for the maintenance and distribution of the PypeIt software package for spectroscopic data reduction.The project will use spectroscopic data from the Keck telescope for 200 quasar sightlines to study the intergalactic medium (IGM). The quasars are all at redshifts greater than 6. The spectroscopic analysis will allow for the identification of the local ionization status of the IGM as well as identifying evidence of enrichment of the IGM with metals from the first supernovae. By identifying the local ionization status around the quasars, the project will also provide a history of the radiative history of the quasar -- thus allowing for a better understanding of how these supermassive black holes grew to such large masses within 800 Myr after the Big Bang. The project will conduct end-to-end analyses encompassing observations, theoretical modeling, state-of-the-art simulations, and Bayesian inference to provide a solid methodological footing for study of the epoch of reionization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.