CAREER: Linking the IGM and Galaxies Near Reionization

130亿年前，宇宙是一个非常不同的地方。星系刚刚开始从大爆炸中产生的物质形成，这些星系发出的强烈辐射正在燃烧着弥漫在深空中的氢气迷雾。在不到10亿年的时间里，雾已经消散，年轻的星系生活在一个紫外线可以在太空中自由传播的宇宙中。这种气体在深空的转变被称为“宇宙再电离”，在早期宇宙中是一个里程碑式的事件。通过研究再电离，我们不仅了解了宇宙中物质的历史，而且了解了第一批星系的形成。这个项目的目标是将我们在再电离过程中在深空中看到的变化与第一批星系本身的特征联系起来。我们如何将对星系和深空的观测结合起来，以更多地了解这个宇宙历史时代？再电离在宇宙中留下了什么印记？PI将使用世界上最大的望远镜来直接探测宇宙历史早期同一地区的星系和星际气体。这些观测将与最先进的计算机建模相结合，以更好地了解宇宙再电离是如何发生的，以及它对早期星系和深空物质的影响方式。在这项研究的基础上，PI将把他的观察专长整合到当地的高中和本科教育中。该计划的一个关键要素是在加州大学河滨分校建立一个校园天文台。这将是美国为数不多的提供光谱学的此类设施之一，光谱学是科学和工业中使用最广泛的技术之一，将被用来促进南加州服务不足的群体参与STEM。在大爆炸大约10亿年后，宇宙经历了一场全球变革。第一批星系是在一个充满暗物质和冷中性气体的宇宙中形成的。然而，当来自这些星系的辐射渗透到深空时，气体被电离和加热，使宇宙对紫外线光子透明。130亿年后，深空中的气体仍然高度电离。因此，早期从中性到电离的转变是宇宙中物质的最后一次相变。这种被称为“再电离”的转变是宇宙史上的一件大事。这一提议的目标是通过同时研究深空气体和嵌入其中的星系来确定再电离发生的时间和方式。PI将使用世界上最大的望远镜来研究星系(通过广域成像)和星系间气体(通过吸收线光谱)在再电离过程中和之后的相同宇宙体积。光谱学也将被用来研究星系内部和周围的气体。这将是第一次将深空演化条件与驱动演化的来源直接联系起来的观测结果。通过进一步将数据与最先进的建模相结合，该项目将更好地理解宇宙再电离是如何发生的，以及它是如何塑造整个宇宙的早期星系和星际物质的。在这项研究的基础上，PI将通过在加州大学河滨分校创建一个校园天文台，将他的观测专业知识整合到当地的高中和本科教育中。这将是美国为数不多的提供光谱学的此类设施之一，光谱学是科学和工业中使用最广泛的技术之一，将用于在南加州服务不足的群体中促进STEM参与。该奖项反映了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。

Thirteen billion years ago the Universe was a very different place. Galaxies were just beginning to form from the matter created in the Big Bang, and the intense radiation emitted by these galaxies was burning away the fog of hydrogen gas permeating deep space. In less than one billion years the fog had cleared, and the young galaxies lived in a Universe where ultraviolet radiation could travel freely through space. This transformation of the gas in deep space is known as "cosmic reionization", and it was a landmark event in the early Universe. By studying reionization we learn not only about the history of matter in the Universe, but about the formation of the first galaxies. The goal of this project is to connect the changes we see happening in deep space during reionization to the characteristics of the first galaxies themselves. How can we combine observations of galaxies and deep space to learn more about this era of cosmic history? What imprints on the Universe does reionization leave behind? The PI will use the world's largest telescopes to directly probe both galaxies and intergalactic gas over the same regions early in cosmic history. The observations will be combined with state-of-the art computer modeling to better understand how cosmic reionization occurred and the ways in which it impacted early galaxies and the matter in deep space. Building on this research, the PI will integrate his observational expertise into local high-school and undergraduate education. A key element of this program will be the creation of a campus observatory at UC Riverside. This will be one of the few such facilities in the country to offer spectroscopy, one of the most broadly used techniques in science and industry, and will be used to promote STEM engagement among underserved groups in Southern California.Roughly one billion years after the Big Bang the Universe underwent a global transformation. The first galaxies formed in a Universe filled with dark matter and cold, neutral gas. As the radiation from these galaxies permeated deep space, however, the gas was ionized and heated, rendering the Universe transparent to ultraviolet photons. Thirteen billion years later the gas in deep space is still highly ionized. The early transition from neutral to ionized was therefore the last phase transition of matter in the Universe. Known as "reionization", this transformation was a key event in cosmic history. The goal of this proposal is to determine when and how reionization occurred by simultaneously studying the gas in deep space and the galaxies embedded within it. The PI will use the word's largest telescopes to study galaxies (via wide-field imaging) and intergalactic gas (via absorption-line spectroscopy) in the same cosmic volumes during and after reionization. Spectroscopy will also be used to study the gas in and around galaxies themselves. These will be the first observations to directly connect the evolving conditions in deep space to the sources driving the evolution. By further combining data with state-of-the-art modeling, this project will provide a better understanding of how cosmic reionization occurred and the ways in which it shaped early galaxies and intergalactic matter throughout the Universe. Building on this research, the PI will integrate his observational expertise into local high-school and undergraduate education by creating a campus observatory at UC Riverside. This will be one of the few such facilities in the country to offer spectroscopy, one of the most broadly used techniques in science and industry, and will be used to promote STEM engagement among underserved groups in Southern California.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.