LADUMA: Reaching the Highest Redshifts with the Deepest HI Survey

LADUMA：通过最深入的 HI 调查达到最高的红移

• 批准号: 2308161
• 负责人: Andrew Baker
• 金额: $ 39.16万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2308161&HistoricalAwards=false
• 关键词: LADUMA; Reaching; Highest; Redshifts; Deepest

Since their formation in the early universe, galaxies have been converting their gas reservoirs - almost entirely composed of atomic (HI) and molecular hydrogen (H2) - into stars. Astronomers have formed an impressively detailed picture of this process, including the "hydrogen cycle" by which atomic and molecular gas transition from one form to the other and back again. The study of H2 in extremely distant (z 3) galaxies has been revolutionized by the Atacama Large Millimeter Array (ALMA), which takes advantage of highly luminous "tracer" molecules like carbon monoxide (CO). To probe the HI content of galaxies astronomers must rely on the much weaker 21 cm "spin-flip" transition of HI, which has effectively restricted studies to the local (z 0.2) universe. This project's goal is to extend this HI census in galaxies to the unprecedented redshift of z = 1.45 and fill a crucial gap in our current understanding of HI’s role in galaxy evolution through the Looking At the Distant Universe with the MeerKAT Array (LADUMA) survey. The project, jointly led by the PI, has been awarded 3,424-hours of high-priority time with the 64-element MeerKAT radio telescope in South Africa to image a single ultra-deep pointing in the Extended Chandra Deep Field South. Supporting observations will be used to allow HI "stacking" observations as well as discriminating HI from OH megamaser emission. All survey data will be publicly released. This project will allow continued U.S. leadership in Square Kilometer Array (SKA) precursor science. The award will also support the training of a graduate student in cutting-edge science as well as a new outreach program to community colleges in New Jersey. Results will be derived from both direct HI spectral line detections and by “stacking” samples of galaxies with previously measured positions and redshifts. The latter will allow LADUMA to achieve its full potential for studying HI out to z = 1.45, at least in a statistical sense. The project also encompasses the identification of OH megamaser “interlopers” in the HI sample that will be used to trace the cosmic history of gas-rich mergers out to z = 1.86. These research activities will benefit from detailed comparisons to theoretical models and are well-matched to the “cosmic ecosystems” theme of the recently released Astro2020 Decadal Survey on Astronomy and Astrophysics, including that theme’s priority science area (“unveiling the hidden drivers of galaxy growth”), a science question (“How do gas, metals, and dust flow into and out of galaxies?”), as well as a critical discovery area prioritized for galaxy evolution research (“mapping the circumgalactic medium and the intergalactic medium in emission”).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.

自从早期宇宙形成以来，星系一直在将其气库（几乎完全由原子（HI）和分子氢（H2）组成）转化为恒星。天文学家已经对这一过程形成了令人印象深刻的详细描述，包括原子和分子气体从一种形式转变为另一种形式并再返回的“氢循环”。阿塔卡马大型毫米波阵列 (ALMA) 彻底改变了极远 (z 3) 星系中 H2 的研究，该阵列利用了一氧化碳 (CO) 等高亮度“示踪”分子。为了探测星系的 HI 含量，天文学家必须依赖于 HI 较弱的 21 厘米“自旋翻转”跃迁，这实际上限制了对局部 (z 0.2) 宇宙的研究。该项目的目标是将星系中的 HI 普查扩展到 z = 1.45 的史无前例的红移，并通过 MeerKAT 阵列观察遥远的宇宙 (LADUMA) 巡天填补我们目前对 HI 在星系演化中的作用的理解中的一个关键空白。该项目由 PI 联合领导，获得了使用南非 64 单元 MeerKAT 射电望远镜 3,424 小时的高优先时间，以对扩展钱德拉深空南区的单个超深指向进行成像。支持观测将用于允许 HI“叠加”观测以及区分 HI 和 OH 巨型脉泽发射。所有调查数据都将公开发布。该项目将使美国继续在平方公里阵列（SKA）先驱科学领域保持领先地位。该奖项还将支持尖端科学领域研究生的培训以及新泽西州社区大学的新外展计划。结果将来自直接 HI 谱线检测以及通过“堆叠”具有先前测量的位置和红移的星系样本。后者将使 LADUMA 能够充分发挥研究 z = 1.45 的 HI 的潜力，至少在统计意义上是这样。该项目还包括识别 HI 样本中的 OH 巨型脉泽“闯入者”，该样本将用于追踪 z = 1.86 范围内富含气体合并的宇宙历史。这些研究活动将受益于与理论模型的详细比较，并且与最近发布的 Astro2020 天文学和天体物理学十年调查的“宇宙生态系统”主题非常匹配，包括该主题的优先科学领域（“揭示星系增长的隐藏驱动因素”）、科学问题（“气体、金属和尘埃如何流入和流出星系？”）以及一个关键发现领域 优先用于星系演化研究（“绘制环绕星系介质和发射中的星系间介质的地图”）。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。