Collaborative Research: Finding the Gas that Lights up Galaxies

合作研究：寻找照亮星系的气体

• 批准号: 1109447
• 负责人: Jason Prochaska
• 金额: $ 15.55万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1109447&HistoricalAwards=false
• 关键词: Collaborative; Research; Finding; Gas; Lights

Damped Lyman-alpha (DLA) systems, layers of low-ionization gas with neutral hydrogen column densities characteristic of modern, gas-rich galaxies, are frequently detected in spectra of background quasars. DLA systems are important probes of the history of galaxy formation and heavy-element enrichment in the universe. The proposing team plans to continue their ongoing work on DLA systems in this project, which has three major components: (1) A survey for DLAs at redshifts near 5. The team will measure ionic column densities, in order to track the build-up of metals in these first galaxies and the evolution of the neutral gas, and will search for a decrease in ionization level close to the re-ionization epoch. (2) A search for 158-micron emission from singly-ionized carbon in galaxies at redshifts near 2, using the ALMA observatory. The targeted galaxies are already known to have [CII] absorption; ALMA observations will connect properties of the gas detected in emission and in absorption to constrain their sizes, dynamics, and star formation rates. Numerical simulations will also be used to predict the [CII] emission properties of galaxies at higher redshift. (3) Imaging far ultraviolet (FUV) light from DLAs. The team will use stacked images of Lyman-break galaxies at redshifts between 1 and 5 identified in the Hubble ultra-deep field to search for low surface-brightness emission. They plan also to exploit the chance alignment of a DLA with a higher redshift, optically-thick absorber to obtain imaging and spectroscopy of the star-forming regions in the FUV and estimate the star formation rate, size and morphology of the galaxy. The project will support the work and training of two graduate students, and the collaborating Principal Investigators will participate in outreach talks in various venues, including a charter minority-serving high school and a science festival for middle school girls. They maintain a public website dedicated to DLA science targeted to both the general public and the research community. The team intends to release all of the high-resolution spectra obtained in this program through the website within 2 years of the first observations.

阻尼莱曼-α（DLA）系统是低电离气体层，具有现代富含气体星系的中性氢柱密度特征，经常在背景类星体的光谱中检测到。 DLA 系统是研究宇宙中星系形成和重元素富集历史的重要探测器。提议团队计划在该项目中继续开展 DLA 系统工作，该项目由三个主要部分组成：（1）对红移接近 5 处的 DLA 进行调查。该团队将测量离子柱密度，以跟踪这些第一批星系中金属的积累和中性气体的演化，并将寻找接近再电离纪元的电离水平的降低。 (2) 使用 ALMA 天文台寻找红移接近 2 的星系中单电离碳的 158 微米发射。已知目标星系具有 [CII] 吸收； ALMA 观测将把发射和吸收中检测到的气体特性联系起来，以限制它们的大小、动力学和恒星形成速率。数值模拟还将用于预测红移较高的星系的 [CII] 发射特性。 (3) 对来自 DLA 的远紫外 (FUV) 光进行成像。该团队将使用哈勃超深场中确定的红移在 1 到 5 之间的莱曼断裂星系的叠加图像来寻找低表面亮度发射。他们还计划利用 DLA 与更高红移、光厚吸收体的偶然排列来获得 FUV 中恒星形成区域的成像和光谱，并估计星系的恒星形成速率、大小和形态。该项目将支持两名研究生的工作和培训，合作的首席研究员将参加在不同场所的外展演讲，包括一所特许少数族裔服务高中和一个初中女生科学节。他们维护着一个专门针对公众和研究界的 DLA 科学公共网站。该团队打算在首次观测后的两年内通过网站发布该计划中获得的所有高分辨率光谱。