Collaborative Research: Dwarf Galaxies Over Cosmic Time

矮星系是所有星系中最小、质量最小的。尽管如此，它们仍然是天体物理学中几个重要问题的核心，包括恒星的形成和化学浓缩，它们作为大爆炸的“积木”，以及负责电离大爆炸遗留下来的星际氢，结束宇宙所谓的“黑暗时代”的主要候选者。在星系类型中，矮星的暗物质与普通物质的比例也是最大的。不幸的是，我们对矮星的了解大多来自靠近我们银河系的卫星星系。这一奖项将支持对附近矮小星系的继续研究，以及将详细研究扩展到半径为500万秒的星系群中的数百颗矮星(也称为“局部体积”)。它还将支持三名研究生，并与亚利桑那州图森市一所服务于少数族裔的社区学院继续合作。研究人员计划调查局域体积内的矮星系群，以及那些位于可观测宇宙中途的矮星系群。这将使用两个半球的广视场、高分辨率、多目标光谱仪和由NSF支持建造的新的积分场单元(IFU)光谱仪-麦哲伦积分场单元(IFUM)-具有独特配置的空间和光谱分辨率模式来观测这些区域中的矮小星系。主要的科学目标包括：1)通过多历元光谱学绘制银河系卫星内的暗物质晕图，识别短周期双星，并有效地对低成员密度的外层区域进行采样；2)分析银河系卫星低金属度的详细化学丰度模式--包括那些由中子星合并等罕见事件的r过程元素严重富集的恒星；3)将新的光谱学与地面和天基成像相结合，在局部体积中量化银河系类似物周围卫星群的丰度、体积速度、内部化学动力学和质量-金属度关系；4)首次测量z~2处透镜状矮星系的恒星形成率、金属丰度和内部运动学。所得到的样品将为将附近的矮星系群置于真正的宇宙学背景下提供第一个基础，使关于矮星系形成和演化的第一个可靠的结论不受我们在本地小组中所处位置的情况的偏见。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。

Dwarf galaxies are the smallest and least massive of all galaxies. They are nonetheless central to several important issues in astrophysics, including star formation and chemical enrichment, their role as "building blocks" of large, and as prime candidates responsible for ionizing the intergalactic hydrogen left over from the Big Bang, ending the universe's so-called "Dark Ages." Dwarfs also have the largest ratio of dark-to-ordinary matter among the galaxy types. Unfortunately, our knowledge of dwarfs is mostly drawn from satellites galaxies that are close to our Milky Way galaxy. This award will support continued investigations of nearby dwarf galaxies as well as an expansion of detailed studies to the hundreds of dwarfs in galaxy groups within a radius of 5 million parsecs (aka the "Local Volume"). It will also support three graduate students and a continuing partnership with a minority-serving community college in Tucson, AZ. The researchers plan to investigate dwarf galaxy populations within the Local Volume as well as those halfway across the observable Universe. This will be done using wide-field, high-resolution, multi-object spectrographs in both hemispheres and a new Integral Field Unit (IFU) spectrograph constructed with NSF support - the Integral Field Unit for Magellan (IFUM) - with uniquely configurable spatial and spectral resolution modes to observe dwarf galaxies in these regimes. Primary science goals include 1) mapping Dark Matter halos within Milky Way satellites via multi-epoch spectroscopy that identifies short-period binary stars and efficiently samples outer regions of low member density; 2) analyzing detailed chemical abundance patterns at low metallicities characteristic of Milky Way satellites—including those dominated by stars showing heavy enrichment by r-process elements from rare events like neutron star mergers; 3) combining new spectroscopy with ground and space-based imaging to quantify the abundance, bulk velocities, internal chemo-dynamics and mass-metallicity relation of satellite populations around Milky Way analogs in the Local Volume; 4) obtaining the first measurements of star formation rates, metallicity, and internal kinematics within lensed dwarf galaxies at z ~ 2. The resulting samples will provide the first basis for placing the nearby dwarf galaxy population into a truly cosmological context, enabling the first robust conclusions about dwarf galaxy formation and evolution that are not biased by the circumstances of our position within the Local Group.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.