Galactic Outflows from the First Starbursts and their Observational Signature

由于光速有限，天文学家可以通过观察很远的地方的物体来回顾过去。这使他们能够测试宇宙从137亿年前的大爆炸到现在的演化理论。这些理论中一个悬而未决的问题是，第一批星系是如何从大爆炸遗留下来的几乎均匀的中性气体氢和氦中形成的。该项目旨在使用复杂的计算机模型来获取大爆炸在宇宙中留下的初始条件，并跟踪它们在新形成的星系中形成第一代恒星时的演变。这些恒星的超新星爆炸反过来又会驱动来自星系的风，这些风会用超新星产生的更重的元素丰富星系之间的物质。该项目将提供早期星系观测特征的估计，以及来自遥远类星体的光线上重元素的印记。尽管目前的望远镜无法研究宇宙演化的这一时期，因为恒星和星系是如此暗淡，但詹姆斯·韦伯太空望远镜等新仪器将能够观测到这些极其微弱的物体，因此这里所做的工作将有助于指导观测计划的制定，从而在新仪器可用时最佳地利用它们。该项目的目标是研究现代天体物理学中一个重要而开放的问题：第一个星系的集合。从大爆炸对早期宇宙的影响来看，星系形成的时代是我们对宇宙演化和结构发展的理解中仍然存在的空白之一。具体来说，该项目将研究由超新星驱动的星系风的作用，即星暴驱动的恒星反馈，对再电离的启用。流体动力学模拟将阐明星爆激发的星际介质的物理学和新产生的金属的力学。从模型中合成的光谱将用于识别矮星系中高红移星暴的特征。此外，模型将提高我们对高红移类星体光谱吸收线所见证的高红移星系间介质金属富集的理解。这项工作将成为解释JWST观测结果的第一步，并将成为下一代大型地面望远镜以及对银河系和其他本星系群中极度缺乏金属的恒星进行现场测量的第一步。此外，研究生将接受理论物理以及数值模拟和可视化的前沿技术方面的培训。这些技能在其他依赖于多尺度建模和大规模科学计算的学科中也至关重要，涵盖从医学成像和地下成像到高能量密度过程的工程和验证等领域。此外，项目团队将为大约60名研究生组织为期五天的暑期学校，主题是“高红移前沿的数值天体物理学”。

Due to the finite speed of light, astronomers can literally look back in time by observing objects at very large distances. This allows them to test theories about the evolution of the universe essentially from the time of the Big Bang, nearly 13.7 billion years ago, to the present. One of the outstanding open questions in these theories is how the first galaxies formed out of the nearly uniform neutral gas of hydrogen and helium left over from the Big Bang. This project aims to use sophisticated computer models to take the initial conditions imprinted on the universe by the Big Bang and follow their evolution as the first generation of stars are formed in newly-formed galaxies. Supernova explosions of these stars will, in turn, drive winds from the galaxies that will enrich the material between galaxies with heavier elements produced in the supernovas. The project will provide estimates of observational signatures of the early galaxies and the imprint of the heavy elements on the light from distant quasars. Although this epoch of the universe's evolution cannot be studied with current telescopes because the stars and galaxies are so dim, new instruments such as the James Webb Space Telescope will be able to observe these extremely faint objects so the work done here will help guide the crafting of observational programs thereby optimally utilizing the new instruments when they are available.The goal of this project is to investigate a significant and open question in modern astrophysics: the assembly of the first galaxies. The epoch of galaxy formation is one of the remaining gaps in our understanding of the evolution of the universe and the development of structure from the imprint of the Big Bang on the early universe. Specifically, the project will study the role of galactic winds driven by supernovae, i.e., starburst-driven stellar feedback, on the enabling of re-ionization. Hydrodynamic simulations will elucidate the physics of the starburst-energized interstellar medium and the mechanics of newly-created metals. Synthetic spectra from the models will be used to identify the signatures of high-redshift starbursts in dwarf galaxies. Furthermore, models will improve our understanding of metal enrichment of the high-redshift intergalactic medium witnessed by absorption lines in the spectra of high-redshift quasars. This work will be a first-step precursor for the interpretation of observations taken with JWST and will the next generation of large ground-based telescopes as well as in-situ measurements of extremely metal-poor stars in the Milky Way and other Local Group galaxies. In addition, graduate students will be trained for careers in theoretical physics and also in cutting-edge techniques of numerical simulation and visualization. These skills are also vital in other disciplines that rely on multi-scale modeling and large-scale scientific computing, spanning areas from medical imaging and subsurface imaging to engineering and validation of high-energy-density processes. In addition, the project team will organize a five-day summer school for approximately 60 graduate students on "Numerical Astrophysics at the High-Redshift Frontier."