Uncovering the Origin and Evolution of Dwarf Galaxies

天体物理学中一个长期存在的问题是了解星系在其一生中如何形成和发展。 这种理解对于揭示我们宇宙的历史和深入了解我们银河系的起源是必要的。 许多研究项目都致力于解开这些谜团。 对附近矮星系和非常遥远星系的观测掌握了有关宇宙最初十亿年星系形成性质的线索，这些第一批星系正在被哈勃太空望远镜探测到，并将随着 2018 年詹姆斯韦伯太空望远镜的投入使用而得到进一步阐明。为了准确解释和连接这些附近和非常遥远的星系观测结果，考虑整个恒星形成历史的精确计算机模拟至关重要。 该项目的目的是对附近的矮星系和遥远的超漫射星系的形成过程进行详细的计算机模拟。 这些模拟将追踪矮星系完整的恒星形成历史，包括它们最早的恒星和星系祖先。 该项目满足了发展美国在天体物理学科学领导地位的国家需要。 该项目还将通过直接培训学生计算天体物理学、高性能计算和软件工程来加强美国科学劳动力，这将使这些学生在竞争激烈的就业市场中脱颖而出。 此外，研究者的研究活动将融入到K--12学校和其他公共场所的天体物理学教学中，如天文馆、电视节目和在线学习环境，让观众能够以视觉直观的方式消化计算天体物理学的最新进展。从技术上讲，该项目有以下目标：（1）探索星团环境中超弥散星系的形成场景，并确定它们是否与星团的形成顺序有关。矮球状星系； （2）构建新颖、高效、准确的辐射传输方法； (3) 将矮星系形成和演化的高红移环境与当今的特征——恒星形成历史、金属丰度分布函数、恒星运动学以及[α/Fe]与[Fe/H]演化联系起来； （4）确定矮星系中第一批恒星和贫金属恒星之间的化学联系。 该项目将支持混合辐射传输求解器的开发，该求解器结合了光线追踪方法和矩方法的优点。 该方法将用于孤立矮星系的一系列辐射流体动力学模拟，在其完整的恒星形成之后，从单个大质量无金属恒星开始。 该项目过程中产生的模拟数据以及各种数据产品将通过新生的国家数据服务公开。 这些数据将可供天体物理学研究界使用，并使研究人员能够解决比该项目本身更广泛的问题。

A longstanding problem in astrophysics is to understand how galaxies form and develop throughout their lifetimes. Such understanding is necessary to uncover the history of our Universe and to gain insight into the origin of our own Milky Way Galaxy. Many research projects are centered on unraveling these mysteries. Observations of nearby dwarf galaxies and of very distant galaxies hold clues about the nature of galaxy formation during the first billion years of the Universe, and these first galaxies are being detected by the Hubble Space Telescope and will be further elucidated with the commissioning of the James Webb Space Telescope in 2018. To accurately interpret and connect these nearby and very distant galaxy observations, precise computer simulations that consider the entire star formation history are essential. The purpose of this project is to make detailed computer simulations of the formation process of nearby dwarf and distant ultra-diffuse galaxies. These simulations will track the complete star formation history of dwarf galaxies including their earliest stellar and galactic ancestors. This project meets the national need to develop US scientific leadership in astrophysics. This project will also strengthen the US science workforce by directly training students in computational astrophysics, high performance computing, and software engineering, which will enable these students to excel in a competitive job market. In addition, the investigators' research activities will be integrated into the teaching of astrophysics in K--12 schools and other public venues, such as planetariums, television shows, and online learning environments, where the audience can digest the latest advances in computational astrophysics in a visual and intuitive manner.More technically, this project has the following goals: (1) to explore formation scenarios for ultra-diffuse galaxies in cluster environments and to determine whether they are related to the formation sequence of dwarf spheroidal galaxies; (2) to construct novel, efficient, and accurate methods for radiation transport; (3) to correlate the high-redshift environment of dwarf galaxy formation and evolution to present-day characteristics---star formation histories, metallicity distribution functions, stellar kinematics, and [alpha/Fe] vs. [Fe/H] evolution; and (4) to determine the chemical connection between the first stars and metal-poor stars in dwarf galaxies. This project will support the development of a hybrid radiation transport solver that incorporates the advantages of both ray tracing methods and moment methods. This method will be utilized in a suite of radiation hydrodynamics simulations of isolated dwarf galaxies, following their complete star formation, starting with individual massive metal-free stars. The simulation data produced during the course of this project, as well as various data products, will be made publicly available through the nascent National Data Service. These data will be usable by the astrophysical research community and will enable researchers to address a much broader range of questions than this project alone.