Stars and Dark Matter in the Halo of the Milky Way

这项工作解决了银河系的形成和结构，特别关注星系晕。晕星的分布、运动学和化学成分可以用来追溯小星系合并和星星协形成晕的形成历史。银河系与矮星系或星团的潮汐相互作用也导致了潮汐剥离的恒星，现在可以追溯到银河系晕中的潮汐流。这从恒星运动和暗物质的分布来表征银河系的引力势。利用斯隆数字巡天（SDSS，SDSS II，SDSS III）的光度和光谱数据以及研究人员在以前的工作中开发的方法，搜索新的潮汐流，并更好地表征已知的潮汐流。这项研究的结果将导致银河系晕的三维密度模型，包括其光滑的组成部分，流和其他子结构，在SDSS成像的12，600平方度的高银河纬度天空。利用这些观测数据建立了银河系中球状星团和矮星系潮汐碎片流中恒星密度分布的真实空间模型。的光环。当结合径向速度时，这些数据将更好地约束银河系的引力势。这反过来又有助于通过同时将轨道和N体模拟与多个潮汐碎片流相匹配来确定暗物质的密度结构。一次考虑一个以上的潮汐碎屑流是一个优点，并且使用更现实的潜在模型。包括恒星沿着潮汐碎片流的分布特性和密度，而不是仅仅使用它们的平均位置和速度，这是旨在限制我们星系中引力晕势和质量分布的模型的另一个优势。两名研究生和3名本科生研究人员将参与该项目，这将有助于培养下一代科学家。主要研究者有一个强大的教育和推广计划，继续作为这项工作的一部分。与达德利天文台，大首都地区教师中心和夏季@伦斯勒项目办公室合作，25名K-12教师将能够上课，把天文学带到教室。该项目还支持由首席研究员管理的MilkyWay@home网站，该网站直接涉及来自166个国家的约40 000人的志愿计算社区，他们为银河系研究贡献了数百万亿次浮点运算的计算能力。

This work addresses the formation and structure of the Milky Way galaxy with particular focus on the galactic halo. The distribution, kinematics, and chemical composition of halo stars can be used to back-track the formation history of the halo which formed by mergers of small galaxies and star associations. The tidal interaction of the Milky Way galaxy with dwarf galaxies or stellar clusters also led to tidally stripped stars which are now traceable as tidal streams in the galactic halo. This characterizes the galactic gravitational potential from stellar motions and the distribution of dark matter. New tidal streams are searched for and known streams better characterized using photometric and spectroscopic data from the Sloan Digital Sky Survey (SDSS, SDSS II, & SDSS III) and methodologies developed in previous work by the investigators. The results from this study will lead to three dimensional density model of the Milky Way halo, including its smooth component, streams and other substructure, over the 12,600 square degrees of high Galactic latitude sky imaged by the SDSS. The observations are used to build a realistic spatial model of the density distribution of stars in spheroid globular cluster and dwarf galaxy tidal debris streams in the Milky Way?s halo. When combined with radial velocities, these data will better constrain the gravitational potential of the Milky Way. This in turn helps to determine the density structure of the dark matter by matching orbits and N-body simulations to multiple tidal debris streams simultaneously. It is an advantage to consider more than one tidal debris stream at a time and that more realistic potential models are used. Including the distribution properties and density of stars along the tidal debris stream rather than only using their average position and velocity is another advantage for models that aim to constrain the gravitational halo potential and the mass distribution in our galaxy. Two graduate students, and 3 undergraduate student researchers will participate in this project which will help to train the next generation of scientists. The principal investigator has a strong education and outreach program which continues as part of this work. In collaboration with the Dudley Observatory, the Greater Capital Region Teacher Center, and the Summer@Rensselaer program office, twenty-five K-12 teachers will able to take classes to bring astronomy in the class room. This projects also supports the MilkyWay@home web site run by the principal investigator, which directly involves a volunteer computing community of about 40,000 people from 166 countries, who contribute hundreds of TeraFLOPS of computing power to Milky Way research.