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

天文学家想要观测宇宙黎明，也就是第一批恒星和星系形成的时候。这些观测将解决许多关于星系如何形成的悬而未决的问题，但由于距离极远，时间段尚未被观测到。首席调查员(PI)雅各布斯和他的团队正在研究观测宇宙黎明期间氢气发出的红移21厘米无线电信号的仪器。低频无线电信号非常微弱，因为不仅星系距离遥远，而且它们被附近宇宙中的前景星系遮挡住了。皮雅各布斯和他的团队将为目前正在建造的两台21厘米宇宙学仪器开发先进的仪器校准工具和技术，这两台仪器是再电离阵列的氢纪元(HERA)和欧文斯谷长波长阵列(OVRO-LWA)。为了扩大参与，国际射电协会将继续指导非传统本科生研究体验(RETU)项目的学生，并为其研究生提供津贴，这些学生对完全可被黑客攻击的业余射电望远镜(CHART)项目做出了主要贡献。这些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在银河系观测氢气。系统的噪音地板改善将通过无人机、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的功率谱测量将排除奇异模型，并为第一批恒星和星系的规范模型提供新的约束。PI将领导一个OVRO-LWA宇宙学计划，该计划旨在确定红移18到25处的氢21厘米限制，同时还展示了适用于其他仪器的技术。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.