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，至少部分是通过在早期宇宙中吞噬大量这样的低质量星系而建立起来的。因此，为了重建像我们银河系这样的星系是如何生长的，我们必须描述早期宇宙中的矮小星系的特征。这些年轻版本的今天的矮小星系群体也是来源的主要候选者，这些来源在很大程度上要对大爆炸留下的星际氢进行电离，从而结束宇宙中所谓的“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技术。研究团队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，以及在国际天文学协会的母校为天文学本科生举办的一系列研讨会/指导计划。多单元光谱探测器和近红外光谱仪结合在一起，将能够探测到红移为4-7的最微弱和最年轻的星系，并对其进行光谱表征。特别是，该团队将测量大质量和红移范围内星系的化学丰度，并研究星系的恒星质量与其化学富集度之间的紧密关联，无论是低质量还是高红移，这都不是很好的限制。这将有助于未来利用4MOST半球调查(4HS)对局部宇宙进行大规模研究。该团队还将研究短而猛烈的恒星形成爆发对矮小星系中恒星质量积累的影响。最后，詹姆斯·韦伯太空望远镜将被用来确定极年轻矮小星系的电离光子输出，这些星系预计将存在于传统观测技术的极限之外。这将对低质量星系对宇宙中最后一个主要阶段变化：宇宙电离的贡献产生影响。这一奖项反映了美国国家科学基金会的法定任务，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。

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.