CAREER: Charting the Cosmic Dawn with Next Generation 21cm Arrays

天文学家希望观测宇宙黎明，当第一批恒星和星系形成时。这些观测将解决许多关于星系是如何形成的悬而未决的问题，但由于极端的距离，时间周期尚未被观察到。首席研究员（PI）雅各布斯和他的团队正在研究仪器，以观察宇宙黎明期间氢气发出的红移21厘米无线电信号。低频无线电信号非常微弱，不仅因为星系很远，而且它们被附近宇宙中的前景星系所掩盖。PI Jacobs和他的团队将为目前正在建设的两个21厘米宇宙学仪器开发先进的仪器校准工具和技术，这两个仪器分别是氢再电离时代阵列（HERA）和欧文斯谷长波长阵列（OVRO-LWA）。为了扩大参与，PI将继续指导并为非传统本科生（RENTU）计划的研究经验的学生和他的研究生提供津贴，这些研究生对完全可破解的业余射电望远镜（CHART）计划做出了重大贡献。研究生为高中生和教师提供工具包和专家指导，以便他们能够建造射电望远镜并观察银河系中的氢气。系统性的本底噪声改善将通过无人机、内部校准源和实验室测量结合先进的数据分析管道来解决。HERA功率谱测量将排除奇异模型，并为第一批恒星和星系的正则模型提供新的约束。PI将领导一个OVRO-LWA宇宙学计划，旨在确定氢21厘米的限制在红移18至25，同时也证明技术适用于其他仪器。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的知识价值和更广泛的影响审查标准的支持。

Astronomers want to observe the Cosmic Dawn, when the first stars and galaxies formed. These observations would resolve many open questions about how galaxies came to be, but owing to the extreme distance, the time period has yet to be observed. Principal Investigator (PI) Jacobs and his team are working on instruments to observe the redshifted 21 cm radio signal emitted from hydrogen gas during the Cosmic Dawn. The low frequency radio signals are very faint as not only are the galaxies far away, but they are obscured by foreground galaxies in the nearby universe. PI Jacobs and his team will develop advanced instrument calibration tools and techniques for two 21cm cosmology instruments currently under construction, the Hydrogen Epoch of Reionization Array (HERA) and the Owens Valley Long Wavelength Array (OVRO-LWA). To broaden participation the PI will continue to mentor and provide stipends for students in both the Research Experience for Non-Traditional Undergraduates (RENTU) program and for his graduate students who are leading contributions to the Completely Hackable Amateur Radio Telescope (CHART) program. The graduate students provide kits and expert guidance to high school students and teachers so that they can build a radio telescope and observe hydrogen gas in the Milky Way.The systematic noise floor improvements will be addressed with drones, internal calibration sources, and laboratory measurements combined with advanced data analysis pipelines. The HERA power spectrum measurements will rule out exotic models and provide new constraints on canonical models of the first stars and galaxies. The PI will lead an OVRO-LWA cosmology program which aims to determine hydrogen 21 cm limits at redshifts 18 through 25 while also demonstrating techniques applicable on other instruments.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.