The accretion history of galactic haloes

星系晕的吸积历史

• 批准号: 162315214
• 负责人: Privatdozent Dr. Jürgen Kerp
• 金额: --
• 依托单位: Institut für Physik und Astronomie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/162315214?language=en
• 关键词: accretion; history; galactic; haloes

We propose a systematic study of the physical properties of neutral and ionized gas in the inner and outer halo of the Milky Way. Beside the large neutral gas complexes in the halo (intermediateandhighvelocity clouds; IVCs and HVCs, respectively) there exists a population of partly ionized gaseous structures with low gas column densities that have a substantial area filling factor. The nature of these structures and their role in the Milky Way’s gas accretion history is nearly unexplored. In this project we will combine new, deep HI 21cm data with ultraviolet and optical spectra to study the filling factor and size distribution of such gaseous filaments in the halo at HI column densities below 1019 cm2. For this, we want to establish a comprehensive statistical data base of Milky Way halo absorbers, comprising more than 400 lines of sight. This will reduce any systematically bias naturally introduced by distance ambiguities towards the clouds of interest. Our unique data sample will allow us to realistically estimate the gas accretion rate of the Galaxy and to clarify the currently unknown relation between Milky Way halo clouds and intervening quasar metal absorptionline systems at low and high redshift.

我们提出了一个系统的研究中性和电离气体的物理性质的内晕和外晕的银河系。除了在晕（intermediateandhighvelocityclouds; IVC和HVC，分别）的大型中性气体复合物，存在着一个人口的部分电离的气体结构与低气柱密度，具有相当大的面积填充因子。这些结构的性质及其在银河系气体吸积历史中的作用几乎未被探索。在这个项目中，我们将联合收割机新的，深HI 21厘米的数据与紫外和光学光谱研究的填充因子和大小分布的晕在HI柱密度低于1019厘米2。为此，我们希望建立一个全面的银河系晕吸收器的统计数据库，包括400多条视线。这将减少由距离模糊性自然引入的对感兴趣的云的任何系统偏差。我们独特的数据样本将使我们能够现实地估计银河系的气体吸积率，并澄清目前未知的银河系晕云和干预类星体金属吸收线系统在低和高红移之间的关系。