Collaborative Research: The Circumgalactic Medium: Understanding Observations from Theory

确切地说，星系最初是如何形成的，以及它们在整个生命周期中是如何变化的，这是天体物理学中最不为人所知的问题之一，而了解星系的形成和生命周期是发展最广泛的天文学视角，了解宇宙如何演变到现在的状态的关键。许多项目都以解开这些谜团为中心。该项目的重点是了解环星系介质（CGM），以揭示其在星系生命周期中的作用。PI丘吉尔将根据他的课程“进入最后的边疆”扩大他之前的“更广泛的影响”项目。本课程将学生与美国太空港以及新墨西哥州拉斯克鲁塞斯迅速发展的航空航天和旅游业联系起来。特别强调的是为少数民族学生创造STEM相关的机会，这些学生占新墨西哥州学生人数的45%。新墨西哥州将资助两名研究生。PI Charlton计划将她成功的科幻互动网络天文学课程转化为视频游戏，教授K- 12学生，同时达到宾夕法尼亚州的STEM天文学标准。该项目将支持两名预选的有技能和才华的学生构建游戏，并将其融入当地学校。一名研究生将在宾夕法尼亚州获得资助。CGM是通过观察和分析类星体光谱中的吸收线来理解的。然而，由于对吸收气体的实际性质一无所知，目前的分析方法无法校准。也就是说，我们对CGM及其在星系演化中的作用的累积知识是基于大量未经检验或量化的隐性和显性假设。利用欧拉流体动力学n体宇宙学模拟代码hydroART，该团队将使用类星体吸收线技术，结合对模拟的直接分析，研究具有各种恒星形成和反馈物理模型的高度详细的模拟星系。这些星系的病毒晕质量在10.5 log(M/Msun) 12.5之间，红移在z ~ 0-3之间。该团队旨在解决这些问题：(1)星系内部和周围星系的气相结构与恒星形成和恒星反馈的物理模型之间的关系是什么？(2)生成的星系与全球星系属性相匹配的模型在多大程度上也与观测到的气态储层属性相匹配？(3) CGM如何调控重子周期和星系演化？(4)目前的吸收谱分析方法是否能推断出与模拟中探测到的气体相一致的气体性质（金属丰度、空间运动学分布、气相和气藏质量）？(5)从观测分析推断出的气体性质与实际引起吸收的气体之间的定量关系是什么？(6)这意味着什么？它们如何改变我们对重子周期和星系演化的理解？

Precisely how galaxies initially form and how they change throughout their lifetimes are among the least understood problems in astrophysics, and understanding the formation and life cycle of galaxies is key to developing the broadest astronomical perspective on how the Universe evolved to its present state. Many projects are centered on unraveling these mysteries. This project is focused on understanding the circumgalactic medium (CGM) to uncover its role in the life cycle of galaxies.PI Churchill will expand his previous Broader Impact program based upon his course "Into the Final Frontier." This course links students to Space Port America and the growing aerospace and tourism industry rapidly growing in Las Cruces, New Mexico. Special emphasis is placed on forging STEM related opportunities for minority students, which comprise 45% of New Mexico State's student population. Two graduate students will be supported in New Mexico. PI Charlton plans to transform her successful science fiction, interactive, web astronomy course into a video game to teach K--12 students, while achieving STEM astronomy standards for the state of Pennsylvania. This project will support two pre-selected skilled and talented students to construct the game and integrate it into local schools. One graduate student will be supported in Pennsylvania.The CGM is understood through observations and analysis of absorption lines in the spectra of quasars. However, being blind to the actual properties of the absorbing gas, present day analysis methods are uncalibrated. That is, our cumulative knowledge of the CGM and its role in galaxy evolution is based upon a host of implicit and explicit assumptions that remain untested or quantified. Using the Eulerian hydrodynamic N-body cosmological simulation code hydroART, the team will use the quasar absorption line technique, coupled with direct analysis of the simulations, to study highly-detailed simulated galaxies with various star formation and feedback physical models. The galaxies will range in viral halo mass from 10.5 log(M/Msun) 12.5 and in redshift from z ~ 0-3. The team aims to address these questions: (1) What is the relationship between the gas phase structures in and surrounding galaxies and the physical model for star formation and stellar feedback? (2) How well do models that yield galaxies matching global galaxy properties also match the observed properties of the gaseous reservoirs? (3) How does the CGM regulate the baryon cycle and galaxy evolution? (4) Do current analysis methods of absorption lines yield inferred gas properties (metallicities, spatial-kinematics distributions, gas phases, and gas reservoir masses) that are consistent with the gas being probed in the simulations? (5) What are the quantitative relationships between inferred gas properties from observational analysis and the gas actually giving rise to the absorption? (6) What are the implications and how do they change our understanding of the baryon cycle and galaxy evolution?