Dissecting the Sub-Structured Halo

剖析亚结构光环

• 批准号: 0807945
• 负责人: Steven Majewski
• 金额: $ 74.84万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0807945&HistoricalAwards=false
• 关键词: Dissecting; Sub; Structured; Halo

Dr. Steven Majewski (University of Virginia) and his team will undertake a suite of five major experiments that will both expand the census of known Milky Way halo tidal streams and exploit halo streams for the understanding of galaxy evolution, structure formation and dark matter (DM) on galaxy-scales. These experiments are (1) A study of the chemistry of halo tidal streams using echelle spectroscopy of stream stars at both optical and near-infrared wavelengths to verify the discovery of a metallicity gradient in the leading arm of the Sagittarius stream, (2) A study of the 3-D motions of stream stars contained in a ground-based proper motion survey of 54 near-equatorial Kapteyn Selected Area fields to derive stream orbits and constrain the shape and strength of the Milky Way potential, (3) Undertake a pilot study with the Green Bank Telescope of a sample of M-type giant stars in tidal streams to look for bright water masers that can be used for precision astrometry of tidal streams using the Very Large Baseline Array, (4) A spectroscopic follow-up to the photometric Grid Giant Star Survey, which has already identified a number of previously known and newly discovered halo substructures across both hemispheres of the sky, and (5) More fully characterize the spatial and radial velocity distributions of G and K giant stars in what look to be "classical" stellar halos discovered around the Large and Small Magellanic Clouds by this research group. The stellar component of our Galactic halo provides an important test-bed for theories of galaxy formation. The present "concordance", hierarchical DM cosmologies predict the presence of stellar streams as tidal remnants of accreted sub-halos. Finding and characterizing these streams thus provides crucial information to constrain the nature of the Cold DM-predicted merging history. These streams are also highly sensitive dynamical probes constraining the shape, strength and lumpiness of the halo of the Milky Way, and provide key insights into the chemical evolution of galaxies. A key aspect of this research is that it has been fueled primarily by student leadership and contributions at both the undergraduate and graduate level. Each experiment is being led or will be led by a different graduate student as part of their Ph.D. dissertation.

史蒂文·马格夫斯基（Steven Majewski）（弗吉尼亚大学）和他的团队将进行五个主要实验套件，这些实验将扩大已知的银河系Halo潮汐流的人口普查，并利用Halo流，以了解银河发展，结构形成和暗物质（结构形成和暗物质（ DM）在星系尺度上。 这些实验是（1）使用光学和近红外波长的流星对光晕潮流的化学研究，以验证在射手座流的领先部门发现金属性梯度的发现，（2）A（2）A对54个近乎赤道的Kapteyn选定区域的适当运动调查中包含的流星的3-D运动的研究，以得出流轨道并限制了银河系潜力的形状和强度，（3）进行飞行员使用潮汐流中M型巨星样品的绿色银行望远镜进行研究，以寻找明亮的水层，可使用非常大的基线阵列用于潮汐流的精确星形统计，（4）光谱的随访光度法巨型恒星调查已经确定了在天空的两个半球上的许多先前已知和新发现的光晕子结构，（5）更充分地表征了G和K巨星的空间和径向速度分布该研究小组围绕大小的麦哲伦云发现了“古典”恒星光环。我们银河光环的恒星成分为银河形成理论提供了重要的测试床。目前的“一致性”，分层DM宇宙学预测出现恒星流是吸质亚群的潮汐残留物。因此，查找和表征这些流提供了至关重要的信息，以限制冷DM预测合并历史的性质。这些流也是高度敏感的动力学探针，可约束银河系光环的形状，强度和肿块，并为星系化学演化提供了关键的见解。这项研究的一个关键方面是，它主要是由学生和研究生层面的学生领导和贡献所促进的。 每个实验都被领导或将由其他研究生领导，作为他们的博士学位的一部分。论文。