Harvesting ALFALFA: Tracking the Gas-Rich Halos at z=0

收获苜蓿：追踪 z=0 处富含气体的光环

• 批准号: 1107390
• 负责人: Martha Haynes
• 金额: $ 71.1万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-15 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1107390&HistoricalAwards=false
• 关键词: Harvesting; ALFALFA; Tracking; Gas; Rich

Precisely how galaxies initially form and how they change throughout their lifetime are among the least understood problems in astrophysics. Many projects are centered on unraveling these mysteries. This project aims to provide the first robust census of gas-rich halos over a cosmologically significant volume and intends to provide important insight into how some massive galaxies maintain huge gas reservoirs without converting their gas into stars and how isolated low mass halos are able to retain some atomic hydrogen gas despite their fragile thermal state and shallow potential wells. This proposal is intended to conclude the already initiated survey, previously funded by NSF. The conclusion of the survey was understandably delayed primarily by telescope downtime but should conclude by the fall of 2012.The survey is conducted at the Arecibo radio telescope and uses the Arecibo L-band Feed Array (ALFA), the Arecibo Legacy Fast ALFA (ALFALFA). The survey has already produced results far exceeding the previous survey in this field, and the survey results will help to characterize the mass function of such halos and allow direct comparison with theoretical simulations of Universe in the current Lambda-CDM paradigm. ALFALFA, an extragalactic HI 21 cm line survey, will identify HI-bearing objects found over 7000 square degrees of the high galactic latitude sky out to z 0.06. The public ALFALFA database includes HI line spectra and catalogues of HI line positions, redshifts, velocity widths, and flux densities as well as coordinates and cross-identifications in other digital data sets of the most probable optical counterparts.This project has educational broader impacts as well. Graduate students will be intimately involved in all phases of the project, helping to plan and execute the observing program, developing software for data processing and analysis, producing public data products and interfacing with the Virtual Observatory, as well as undertaking their own science projects. Educational materials that are developed as part of this project will be made available through the existing ALFALFA public web site.

星系最初是如何形成的，以及它们在一生中是如何变化的，这是天体物理学中最不为人所知的问题。 许多项目都集中在解开这些谜团。 这个项目的目的是提供第一个强大的普查富含气体的晕在宇宙学上的显着的体积，并打算提供重要的洞察力，一些大质量星系如何保持巨大的气体水库，而不将其气体转化为恒星，以及如何孤立的低质量晕能够保留一些原子氢气体，尽管他们脆弱的热状态和浅的潜在威尔斯。 该提案旨在结束先前由NSF资助的已经启动的调查。 调查的结论是可以理解的延迟，主要是由于望远镜停机，但应该在2012年秋季结束。调查是在阿雷西博射电望远镜进行，并使用阿雷西博L波段馈电阵列（ALFA），阿雷西博遗产快速ALFA（ALCAFA）。 该调查已经产生了远远超过该领域以前调查的结果，调查结果将有助于描述这种晕的质量函数，并允许与当前Lambda-CDM范式中的宇宙理论模拟进行直接比较。 ALCARFA是一项河外HI 21厘米线测量，将识别在z 0.06的高银河纬度天空7000平方度以上发现的HI轴承物体。 公共的ALCARFA数据库包括HI线谱和HI线位置、红移、速度宽度和通量密度的目录，以及最可能的光学对应物的其他数字数据集的坐标和交叉识别。 研究生将密切参与项目的各个阶段，帮助规划和执行观测计划，开发数据处理和分析软件，制作公共数据产品，与虚拟天文台对接，以及开展自己的科学项目。 作为该项目一部分编制的教育材料将通过现有的ALNOFA公共网站提供。