Charting the history of reionization with radio observations of the early universe

雅各布斯博士被授予NSF天文学和天体物理学博士后奖学金，在亚利桑那州立大学开展研究和教育计划。这项研究的目标是发现第一批恒星的证据，这些恒星被认为是在大爆炸后大约5亿年的某个时候诞生的。这些恒星发出强烈的辐射，烧毁了宇宙中无处不在的氢大气。由于氢占宇宙正常物质的四分之三，这最后一个全球宇宙学过程支撑了大部分关于宇宙学和星系形成的知识。然而，由于早期恒星的极端距离和微弱，在普通星星光下观察这段时间对世界上最好的望远镜提出了挑战。这项研究计划的目标是利用两台最近完成的射电望远镜，探测星系间氢在电离之前和电离期间的射电发射并确定其特征。探测和描述这一“宇宙黎明”的预测无线电特征被天文学界列为首要任务。该项目还将支持一个学生志愿者团，他们将携带便携式天文馆到学校，并将直接参与博物馆和天文馆设施的开发。其中包括最先进的3D天文馆剧院，在最近建造的亚利桑那州立大学天文大楼。数字技术的最新进展允许建造非常大的天线阵列，提供必要的灵敏度来探测宇宙只有300 Mya时氢的无线电发射。在21厘米的波长下发射，辐射被宇宙膨胀拉伸到1.5到3米的观测波长，这取决于观测的时间段。默奇森宽场阵列（MWA）和探测再电离时代的精密阵列（PAPER）都是为了以必要的灵敏度观察这些波长而设计的，并且在很大程度上由国家科学基金会资助，远离干扰人类无线电发射; MWA位于西澳大利亚州，PAPER位于南非的卡鲁沙漠。利用这两台望远镜，雅各布斯博士将对早期宇宙中来自氢的辐射量进行深入的统计测量。部分工作包括进行观测，测量和消除来自其他明亮天体的其他明亮干扰信号，并将这些新知识应用于建造能够直接成像早期宇宙的大型望远镜。这些明亮的干扰信号的测量将形成一个实质性的，有趣的，令人信服的美丽的宇宙图像，并提供了一个基础数据集的展品由学生团体创建的项目的一部分。本科生团队将有两个目标：第一，提高天文学和科学教育本科生的保留率，第二，将天文馆表演带到传统上服务不足的学校和部落中心，这些学校和部落中心无法利用其他更昂贵的项目。

Dr. Jacobs is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at Arizona State University. The goal of the research is to detect evidence of the first stars, thought to be born sometime about 500 Million years after the Big Bang. These stars emitted intense radiation which burned away the universe's pervasive atmosphere of Hydrogen. As hydrogen accounts for three quarters of the normal matter in the universe, this last global cosmological process underpins much of what is known about cosmology and galaxy formation. However, observing this time period in ordinary star light challenges the world's premier telescopes due to the extreme distance and faintness of the early stars. The goal of this research program is to detect and characterize radio emission from intergalactic hydrogen before and during its ionization using two recently completed radio telescopes. Detecting and characterizing the predicted radio signature of this "Cosmic Dawn" was rated as a top priority by the astronomical community. This project will also support a student volunteer corps who will take a portable a planetarium to schools and who will be directly involved in developing elements for museum and planetarium facilities. These include a state of the art 3D planetarium theater, in the recently constructed Arizona State University astronomy building.Recent advances in digital technology allow the construction of very large arrays of antennae which provide the necessary sensitivity to detect radio emission from Hydrogen when the universe was only 300Mya old. Emitted at a wavelength of 21cm, the radiation is stretched by cosmological expansion to an observed wavelength of 1.5 to 3m depending on the time period under observation. Both the Murchison Widefield Array (MWA) and the Precision Array for Probing the Epoch of Reionization (PAPER) have been designed to observe these wavelengths at the necessary sensitivity and are constructed, in large part with funding from the National Science Foundation, far from interfering human radio emission; the MWA is in Western Australia and PAPER is in the Karoo desert of South Africa. Using both telescopes, Dr. Jacobs will compile a deep statistical measure of the amount of radiation coming from Hydrogen in the early universe. Portions of the work include performing observations, measuring and removing other bright interfering signals from other bright astronomical objects, and applying this new knowledge to building larger telescopes capable of directly imaging the early universe. These measurements of bright interfering signals will form a substantial, interesting, and compellingly beautiful image of the universe and provide a foundation data set for exhibits produced by the student corps created as a part of the project. The team of undergraduate students will have two goals: First to improve retention of astronomy and science education undergraduates and second to bring planetarium shows to traditionally underserved schools and tribal centers which cannot take advantage of other, more costly, programs.