Collaborative Research: Dwarf Galaxies Over Cosmic Time

矮星系是所有星系中最小且质量最小的。尽管如此，它们仍然是天体物理学中几个重要问题的核心，包括恒星形成和化学富集、它们作为大型宇宙“基石”的作用，以及作为负责电离大爆炸留下的星际氢、结束宇宙所谓的“黑暗时代”的主要候选者。在星系类型中，矮星系的暗物质与普通物质的比例也是最大的。不幸的是，我们对矮星的了解主要来自靠近银河系的卫星星系。该奖项将支持对附近矮星系的持续研究，并将详细研究扩展到半径 500 万秒差距（又称“本地体积”）内的星系群中的数百个矮星系。 它还将支持三名研究生，并与亚利桑那州图森市的一所少数族裔社区学院建立持续的合作伙伴关系。研究人员计划调查本地体积内以及可观测宇宙中途的矮星系种群。这将使用两个半球的宽视场、高分辨率、多目标摄谱仪和在 NSF 支持下构建的新型整体场单元 (IFU) 摄谱仪 - 麦哲伦整体场单元 (IFUM) - 以及独特的可配置空间和光谱分辨率模式来观察这些区域中的矮星系。主要科学目标包括 1) 通过多历元光谱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部区域进行采样； 2) 分析银河系卫星低金属丰度特征的详细化学丰度模式——包括那些以中子星合并等罕见事件中的r过程元素大量富集的恒星为主的卫星； 3）将新的光谱学与地面和天基成像相结合，量化本地体积中银河系类似物周围卫星群的丰度、体速度、内部化学动力学和质量金属丰度关系； 4) 首次测量 z ~ 2 处透镜状矮星系内的恒星形成率、金属丰度和内部运动学。由此产生的样本将为将附近的矮星系种群置于真正的宇宙学背景中提供第一个基础，从而能够得出关于矮星系形成和演化的第一个可靠结论，而不会因我们在本地组中的位置情况而产生偏差。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

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.