Collaborative Research: Dark Matter and Substructure in the Galactic Halo with Gaia and Multi-Object Spectroscopy

银河系光环包含了我们的家园银河系周围巨大的，看似空无一物的体积。 但光环并不像它看起来那么空。 各种各样的矮星系、恒星流和星星团遍布光环。 这些结构可以揭示暗物质的性质，重元素是如何形成的，以及我们的银河系是如何形成的。 该项目通过将来自大型公共天空调查的数据与将用最先进的地面设施获得的新数据相结合，推进了这一领域。 该项目旨在识别新的恒星结构，然后探测它们的化学和动力学。 结果将测试暗物质和星系形成的竞争模型。 该项目建立在以前NSF在仪器和科学劳动力方面的投资基础上。 该团队将继续运营NSF资助的密歇根/麦哲伦光纤系统（M2 FS）光谱仪，使其他天文学家能够进行创新科学。 这些活动通过继续成功的公众推广计划和培训下一代天文学家来促进科学发展。主要的科学目标包括1）探测微弱和以前未知的星星团、矮星系和银河系晕内的恒星流; 2）测量这些结构内恒星的速度和化学成分;以及3）绘制这些结构的暗物质含量。 为了发现新的天体，该团队将从盖亚空间使命中挖掘数据，利用其前所未有的天空覆盖范围，恒星位置精度和恒星运动测量的组合。 该团队将利用盖亚数据不仅识别新的恒星结构，还将识别已知结构中的稀有恒星。 对于所有这样的目标，研究小组将使用M2 FS光谱仪来测量恒星的速度和化学成分。 最后，该团队将联合收割机结合盖亚和M2 FS数据集，利用多维信息来推断这些结构的暗物质含量和化学演化。 这些研究成果将推进有关暗物质的性质、重元素的起源、最小星系的形成和演化以及我们银河系恒星晕形成过程的知识前沿。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进行评估，被认为值得支持。

The Galactic Halo encompasses the vast, seemingly empty volume surrounding our home galaxy, the Milky Way. But the Halo is not so empty as it appears. A rich variety of dwarf galaxies, stellar streams and star clusters pervade the Halo. These structures can reveal the nature of dark matter, how heavy elements are made, and how our Galaxy formed. This project advances the field by combining data from large public sky surveys with new data to be obtained with state-of-the art ground-based facilities. This project aims to identify new stellar structures, then probe their chemistry and dynamics. The results will test competing models of dark matter and galaxy formation. This project builds on previous NSF investments in instrumentation and the scientific workforce. The team will continue to operate the NSF-funded Michigan/Magellan Fiber System (M2FS) spectrograph, enabling innovative science by other astronomers. These activities promote science by continuing successful public outreach programs and training the next generation of astronomers.The primary scientific objectives include 1) the detection of faint and previously unknown star clusters, dwarf galaxies, and stellar streams within the Milky Way halo; 2) measurement of the velocities and chemical compositions of the stars within these structures; and 3) mapping the dark matter content of these structures. To discover new objects, the team will mine data from the Gaia space mission, exploiting its unprecedented combination of sky coverage, precision of stellar positions, and measurement of stellar motions. The team will use Gaia data to identify not only new stellar structures, but also rare stars within known structures. For all such targets, the team will use the M2FS spectrograph to measure stellar velocities and chemical composition. Finally, the team will combine the Gaia and M2FS data sets, exploiting the multi-dimensional information to infer the dark matter content and chemical evolution of these structures. These results will advance the frontiers of knowledge regarding the nature of dark matter, the origin of heavy elements, the formation and evolution of the smallest galaxies, and the processes that built up the stellar halo of our own Milky Way.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.