A Lyman-alpha View of the Late Stage of Reionization

宇宙大爆炸后不久，宇宙黎明出现了，并形成了第一批恒星，黑洞和星系。 中性氢气在这一时期主导着宇宙。 随着第一批恒星的生命周期结束和第一批黑洞的形成，星系际介质（IGM）被加热，中性氢在再电离时期被电离。 氢的宇宙再电离仍然是现代宇宙学中知之甚少和受限制的前沿之一。 目前对宇宙微波背景辐射和高红移类星体的观测对再电离的限制指向宇宙电离状态的快速变化，从红移z在6到10之间。 这中间的再电离的关键阶段和第一个星系的形成是密切相关的。 对红移z = 6以上星系的观测是许多空间和地面设施和调查的主要科学目标之一，可以为了解宇宙再电离提供关键数据。本项目将对使用Ly-alpha发射星系（LAEs）进行全面的理论研究，该星系可有效地探测到红移z = 6以上，以限制再电离的后期阶段。 由于从这些星系发射的Ly-alpha光子与环星系和星系际介质相互作用，Ly-alpha发射是再电离状态的灵敏探针。 研究人员将联合收割机结合最先进的宇宙学再电离模拟与有效的蒙特卡罗Ly-alpha辐射传输代码，以获得详细和现实的L-alpha发射特性的LAEs在一个大的调查样体积。 主要科学目标包括：（1）研究和设计各种统计数据，以解决如何利用观测到的LAEs的不同方面来探测再电离;（2）实施几种银河风处方，以解决LAEs在再电离期间可见度的主要不确定性之一;（3）提出具体的预测和形成模拟LAE观测，以帮助制定观测策略和指导观测工作。 推进早期结构形成的理解，全面的Ly-alpha辐射传输模型的恒星形成星系的宇宙学体积在整个再电离时代将提供一个坚实的理论基础来解释观测和约束再电离，并将提供支持，以目前和未来的空间和地面为基础的设施和调查。 从这项研究中产生的数据将通过一个指定的网页提供给科学界，用于各种应用。教育方面，本科生将积极参与支持研究计划的项目。 首席研究员将帮助建立犹他州自然历史博物馆和犹他州大学天文台之间的教育和外联合作。 他将丰富博物馆“聚光灯下的科学家”计划中的天文学部分，他还将在校园每周的星星派对上与公众互动。

A short time after the Big Bang, the Cosmic Dawn emerged and featured the formation of the first stars, black holes, and galaxies. Neutral hydrogen gas dominated the Universe during this epoch. As the life cycle of the first stars ended and the first black holes formed, the intergalactic medium (IGM) was heated, and the neutral hydrogen was ionized during the Epoch of Reionization. The cosmic reionization of hydrogen remains one of the poorly understood and constrained frontiers of modern cosmology. Current constraints of reionization from observations of cosmic microwave background and high-redshift quasars point to a rapid change of the ionization state of the universe from a redshift of z between 6 and 10. The crucial stage of reionization in between and the formation of first galaxies are closely linked to each other. Observations of galaxies beyond a redshift of z around 6, one of the main science goals of many space-based and ground-based facilities and surveys, can provide critical data for learning about cosmic reionization.This project will carry out a comprehensive theoretical investigation of using Ly-alpha emitting galaxies (LAEs), efficiently detectable beyond a redshift z around 6, to constrain the late stage of reionization. Because Ly-alpha photons emitted from these galaxies interact with the circumgalactic and intergalactic media, Ly-alpha emission is a sensitive probe of the reionization state. The investigators will combine a state-of-the-art cosmological reionization simulation with an efficient Monte Carlo Ly-alpha radiative transfer code to obtain detailed and realistic L-alpha emission properties of LAEs in a large survey-like volume. The primary science goals include (1) studying and designing a variety of statistics to address how to use different aspects of observed LAEs to probe reionization; (2) implementing several prescriptions of galactic winds to address one of the major uncertainties in the visibility of LAEs during reionization; (3) making specific predictions and forming mock LAE observations to help developing observational strategies and guiding observational efforts. Advancing the understanding of early structure formation, the comprehensive Ly-alpha radiative transfer modeling of star-forming galaxies in a cosmological volume across the reionization epoch will provide a solid theoretical basis to interpret observations and to constrain reionization and will provide support to current and future space- and ground-based facilities and surveys. The data generated from this study will be made available to the scientific community through a designated web page for a variety of applications.Educationally, undergraduate students will be actively involved in projects that support the research program. The principal investigator will help establish a collaboration in education and outreach between the Museum of Natural History of Utah and the Observatory of the University of Utah. He will enrich the astronomy component in the "Scientist in the Spotlight" program at the Museum, and he will also interact with the general public at weekly star parties on campus.