Collaborative Research: Observing the Cosmic Evolution of Neutral Hydrogen

氢是宇宙中最丰富的元素，因此中性氢原子是星系中星际气体的重要组成部分。但也是最具挑战性的研究之一。中性氢发射的微弱性意味着它只能通过大型望远镜的长期观测在附近的宇宙之外被发现。一个新的望远镜具有更高的灵敏度，MeerKAT阵列，将研究星系的中性气体储存如何演变超过三分之二的宇宙历史（即，宇宙时间的最后90亿年）。它将确定星系的中性氢原子含量如何与其恒星的性质，环境和宇宙时代相关。这将与理论预测进行比较，以了解气体如何流入和流出星系，并在星系内形成新的恒星。该研究将支持四所大学的研究生和本科生的培训;研究生将获得计算和统计学、研究导师、STEM学科教育以及各种受众的额外经验。该调查将探测发射到z = 1.45的前所未有的高红移的中性氢（HI）。单个HI检测和叠加HI检测的组合？ 辅以理论建模、多波长观测和丰富的z = 0参考数据集？将探讨（i）重子塔利-费舍尔关系，（ii）HI质量函数，以及（iii）星系HI含量对恒星和暗物质性质的依赖性的演化。在MeerKAT数据中作为强线发射体检测到的OH超脉泽将用于限制富含气体的星系合并的宇宙历史。HI调查数据和用于提供学生培训的教学模块都将作为项目的一部分公开发布。该奖项反映了NSF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。

Hydrogen is the most abundant element in the universe, and neutral hydrogen atoms are thus an important constituent of interstellar gas in galaxies ? but also one of the most challenging to study. The faintness of neutral hydrogen emission means that it can only be detected beyond the nearby universe via long observations with large telescopes. A new telescope with improved sensitivity, the MeerKAT array, will examine how galaxies' neutral gas reservoirs have evolved over two thirds of the universe's history (i.e., the last nine billion years of cosmic time). It will determine how galaxies' neutral atomic hydrogen content relates to the properties of their stars, their environments, and their cosmic epochs. This will be compared with theoretical predictions in order to understand how gas flows into and out of galaxies and forms new stars while inside galaxies. The research will support the training of graduate and undergraduate students at the four universities; graduate students will gain additional experience in computation and statistics, research mentorship, education in STEM disciplines, and outreach to a variety of audiences.This survey will probe neutral hydrogen (HI) in emission to an unprecedentedly high redshift of z = 1.45. The combination of individual and stacked HI detections ? complemented by theoretical modelling, multiwavelength observations, and a rich z = 0 reference dataset ? will probe the evolution of (i) the baryonic Tully-Fisher relation, (ii) the HI mass function, and (iii) the dependence of galaxies' HI content on stellar and dark matter properties. OH megamasers detected as strong line emitters in the MeerKAT data will be used to place constraints on the cosmic history of gas-rich galaxy mergers. Both the HI survey data and the instructional modules used to provide student training will be publicly released as part of the project.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.