Characterizing Low-Mass Galaxies with Spectroscopy Through Cosmic Time

虽然矮星系是所有星系中质量最小的，但它们也是目前为止最常见的星系类型。有令人信服的证据表明，包括银河系在内的大质量星系，至少在一定程度上是通过早期宇宙中大量这样的低质量星系的相互蚕食而形成的。因此，为了重建像我们银河系这样的星系是如何形成的，我们必须描述早期宇宙中的矮星系。这些年轻版本的矮星系也是主要的候选来源，主要负责电离大爆炸遗留下来的星系间氢，结束了宇宙所谓的“黑暗时代”。该奖项将支持地面望远镜和詹姆斯·韦伯太空望远镜的光谱学研究。研究小组将利用这些数据来提高我们对星系形成的理解。该奖项将支持一名研究生的博士工作，以及PI所在机构的天文学本科生系列研讨会/指导计划。多单元光谱探测器和近红外光谱仪一起，将对红移为4-7的最微弱和最年轻的星系进行探测和光谱表征。特别是，该团队将在质量和红移的大范围内测量星系的化学丰度，并研究星系的恒星质量与其化学富集程度之间的紧密关联，这在低质量或高红移时都没有很好的约束。这将有助于为未来第4半球调查（4HS）对当地宇宙的大规模研究提供信息。该团队还将研究矮星系中恒星形成的短暂而剧烈的爆发对恒星质量积累的影响。最后，詹姆斯·韦伯太空望远镜将用于确定极端年轻的矮星系的电离光子输出，这些矮星系预计将在传统观测技术的限制之外存在。这将暗示低质量星系对宇宙中最后一个主要相变的贡献：宇宙再电离。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

While dwarf galaxies are the least massive of all galaxies, they are also by far the most common type in the current epoch. There is compelling evidence that massive galaxies, including the Milky Way, were built up at least in part through the cannibalization of large numbers of such low mass galaxies in the early universe. Therefore, to reconstruct how a galaxy like our own Milky Way grew, we must characterize dwarf galaxies in the early universe. These young versions of today's dwarf galaxy population are also prime candidates for the sources largely responsible for ionizing the intergalactic hydrogen left over from the Big Bang, ending the universe's so-called "Dark Ages." This award will support spectroscopy from ground-based telescopes and the James Webb Space Telescope. The team of researchers will use these data to improve our understanding of galaxy formation. This award will support the PhD work of a graduate student as well as a seminar series/mentoring program for astronomy undergraduates at the PI’s home institution. Together, Multi-Unit Spectroscopic Explorer and Near Infrared Spectrometer will allow the detection and spectroscopic characterization of the faintest and youngest galaxies ever discovered at redshifts of 4-7. In particular, the team will measure chemical abundances for galaxies over a large range in mass and redshift, and study the tight correlation between a galaxy’s stellar mass and its degree of chemical enrichment, which is not well-constrained either at low masses or high redshifts. This will help inform future large-scale studies of the local universe with the 4MOST Hemisphere Survey (4HS). The team will also study the impact of short, violent bursts of star formation on the stellar mass buildup in dwarf galaxies. Finally, the James Webb Space Telescope will be used to determine the ionizing photon output from extremely young dwarf galaxies that are expected to exist just beyond the limits of traditional observational techniques. This will have implications for the contribution of low-mass galaxies to the last major phase change in the universe: cosmic Reionization.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.