Collaborative Research: M31 Satellites Past and Present

合作研究：M31 卫星的过去和现在

• 批准号: 1009882
• 负责人: Steven Majewski
• 金额: $ 29.44万
• 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: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1009882&HistoricalAwards=false
• 关键词: Collaborative; Research; M31; Satellites; Past

Collaborative Research: M31 Satellites Past and PresentAST 1010039, Puragra Guhathakurta, University of California-Santa Cruz (lead)AST-1009882, Steven R. Majewski, University of Virginia Main CampusAST-1009973, James Bullock, University of California-IrvineThis is a comprehensive study of the formation and evolution of the dwarf spheroidal (dSph) satellites of Andromeda (M31). These satellites within the Local Group include the least luminous galaxies known and they can be explored to test ideas about star formation in the smallest dark matter halos and at the earliest times.Extensive data sets on the resolved stellar populations of M31 satellites are combined with state-of-the-art galaxy models in order to learn how the dynamical -, merger -, assembly -, star formation -, and chemical enrichment histories of the current and past M31 satellite systems fit together in the context of the general paradigm of hierarchical galaxy formation. The data for M31 are compared to the satellites and halo population of the Milky Way galaxy for which were previously studied by the investigators. The Milky Way and M31 are both spiral galaxies but have different populations of satellite galaxies for which an explanations needs to be found. The additional data for M31 are important for evaluating solutions to the ?missing satellites problem? in Lambda-Cold Dark Matter (CDM) simulations, where the number of subhalos is predicted to be higher than the number of observed satellites. So far the Milky Way is the only system for which the comparison to models can be made which will change when the results of this study are available.The three principal investigators have a standing collaboration and they have initiated the SPLASH (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) survey with previous support from the NSF. The methods and techniques used here are well established in this collaboration. The SPLASH survey uses the DEep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope and the 4-m telescope with Mosaic CCD wide field Imager at Kitt Peak National Observatory. The survey extends to study red giant branch stars in more satellite galaxies of the Andromeda system. The group has already 139 DEIMOS masks (about 20,000 spectra) and spectroscopy of M31 red giant candidates selected from the imaging data. The goal is to observe another 135 DEIMOS masks to obtain spectra of more than 100 member red giant stars in each of the known and any newly found dSph satellites of M31. Further spectra are thought for about 3,000 stars in M33, a low-luminosity disk satellite interacting with M31; and about 1,000 stars in the NE shelf which is tidal debris from a past M31 satellite associated with the Giant Southern Stream in M31.One part of the work combines spectral and photometric diagnostics to isolate M31 red giants efficiently. Further there are measurements of precision stellar velocities to derive velocity dispersions in dwarf galaxies and tidal streams, which are both kinematically cold subsystems. Measurements of elemental abundances from moderate resolution co-added spectra tare used o constrain the chemical enrichment/star formation histories of M31 satellites. Theoretical models are used to determine the dark matter mass of each dwarf satellite galaxy in M31 to place the observations within a cosmological framework. This will give more data to decipher how the evolution of the Milky Way and M31 can be described in the context of Lambda-CDM cosmology.This work provides another data set for a galaxy system to test Lambda-CDM cosmologies. This will have a broad impact on other fields. The DEIMOS-derived chemical abundances are of interest for stellar population studies community. The new analytical methods developed here provide a foundation for similar studies of resolved stars in other stellar systems, including more distant galaxies to be targeted with the next generation of telescopes.Undergraduate students are participating in the research activities and graduate students work on parts of this project for their theses. This will help to train the next generation of scientists. The researchers make efforts to speak in K-12 classrooms and to reach out to underrepresented high-school and undergraduate students. Research results about the well-known large spiral galaxy Andromeda are well suited to be incorporated into public lectures and presentations which are given by the team members on a regular basis.

合作研究：M31卫星过去和Presentast 1010039，Puragra Guhathakurta，加利福尼亚大学圣克鲁斯大学（LEAD）AST-1009882，Steven R. Majewski，弗吉尼亚大学Main Campusast-1009973，詹姆斯·布洛克大学，加利福尼亚大学 - 伊尔维尼斯大学。研究仙女座（M31）的矮球（DSPH）卫星的形成和演变的研究。本地组中的这些卫星包括已知的最低发光星系，可以探索它们以测试有关最小的暗物质光环和最早的恒星形成的想法。 -Art Galaxy模型，以了解动态 - 合并 - ，组装 - ，恒星形成 - 以及当前和过去M31卫星系统的化学富集历史星系形成。将M31的数据与研究人员先前研究过的银河系的卫星和光晕种群进行了比较。银河系和M31都是螺旋星系，但卫星星系种群不同，需要找到解释。 M31的其他数据对于评估缺失卫星问题的解决方案很重要吗？在Lambda-Cold暗物质（CDM）模拟中，预计Subhalos的数量高于观察到的卫星数量。到目前为止，银河系是唯一可以与模型进行比较的系统，当这项研究的结果可用时会改变。 NSF先前的支持，仙女座的出色光环）调查。此处使用的方法和技术在这项合作中已经建立了良好的确定。 Splash调查使用Keck II望远镜上的深度成像多对象光谱仪（DEIMOS）和4-M望远镜在Kitt National天文台的Mosaic CCD宽田间成像仪。该调查扩展到在仙女座系统的更多卫星星系中研究红色巨型分支星星。该小组已经有139个Deimos面具（约20,000个光谱）和从成像数据中选择的M31红色巨型候选者的光谱。目的是观察另外135个Deimos口罩，以在每个已知和任何新发现的M31卫星中获得100多个成员红色巨星的光谱。人们认为，在M33中，大约3,000颗恒星被认为是一个低亮度磁盘卫星与M31相互作用的光谱。 NE架子上约有1,000颗恒星，这是过去M31卫星与M31中巨型南部溪流相关的潮汐碎片。该作品的一部分结合了光谱和光度诊断，以有效地分离M31红色巨人。此外，还测量了精确的恒星速度，以得出矮星系和潮汐流中的速度分散体，它们都是运动学上的寒冷子系统。使用中等分辨率的元素丰度的测量，使用的光谱使用o限制了M31卫星的化学富集/恒星形成历史。理论模型用于确定M31中每个矮人卫星星系的暗物质质量，以将观测值放置在宇宙学框架之内。这将提供更多数据，以解释如何在Lambda-CDM Cosmology的背景下描述银河系和M31的演变。这项工作为Galaxy System提供了另一个数据集，用于测试Lambda-CDM宇宙学。这将对其他领域产生广泛的影响。 Deimos衍生的化学丰度对于出色的人群研究社区而言是感兴趣的。此处开发的新分析方法为对其他恒星系统中解决的星星的类似研究奠定了基础他们的论文项目。这将有助于培训下一代科学家。研究人员努力在K-12教室里发言，并与代表性不足的高中生和本科生接触。关于众所周知的大型螺旋星系仙女座的研究结果非常适合将团队成员定期进行的公开讲座和演示纳入。