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富集，它们作为大星系的“基石”的作用，以及作为电离大爆炸遗留下来的星系间氢的主要候选者，大爆炸结束了宇宙所谓的“黑暗时代”。在所有星系类型中，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于离银河系很近的卫星星系。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为500万秒差距（又名“局部体积”）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大学继续合作。研究人员计划调查本地体积内的矮星系种群，以及可观测宇宙的中间部分。这将使用两个半球的宽视场，高分辨率，多目标光谱仪和一个新的积分场单元（IFU）光谱仪，该光谱仪由美国国家科学基金会支持建造-麦哲伦积分场单元(IFUM) -具有独特的可配置空间和光谱分辨率模式，以观察这些区域中的矮星系。主要科学目标包括：1)通过多历元光谱学绘制银河系卫星内的暗物质晕，识别短周期双星，并有效采样低成员密度的外部区域；2)分析银河系卫星低金属丰度特征的详细化学丰度模式，包括那些由中子星合并等罕见事件中r过程元素富集的恒星；3)将新的光谱技术与地面和天基成像技术相结合，在局部体积内量化银河系类似物周围卫星种群的丰度、体速度、内部化学动力学和质量-金属丰度关系；4)首次测量了z ~ 2处透镜矮星系的恒星形成速率、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强有力的结论不受我们在本星系群中的位置的影响。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。

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.