The temperature of the circumgalactic and intergalatic medium over cosmic time

宇宙时间内环星系和星系际介质的温度

• 批准号: 2108702
• 负责人: Tae Sun Kim
• 金额: $ 39.22万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2108702&HistoricalAwards=false
• 关键词: temperature; circumgalactic; intergalatic; medium; over

In the early Universe, the intergalactic medium (IGM) is largely filled with diffuse hydrogen and helium gas. The IGM is distributed in a cosmic web of sheets and filaments, separated by voids. Galaxies form at the intersections of these structures and are fed by IGM gas falling onto regions surrounding galaxies called the circumgalactic medium (CGM). Principal Investigators Kim and Wakker will analyze archival data to study the complex interaction between gas accretion from the IGM and galactic outflows in the CGM, which controls star formation efficiency and mediates galaxy evolution. To broaden participation the PIs will organize a series of research related public talks and develop an online exhibit through the University of Wisconsin Space Place. The PIs will also continue to work with local middle and high schools to increase student participation in the annual Science Olympiad tournament.The PIs will estimate the temperature and turbulence of the diffuse CGM/IGM at 2z4 by determining the absorption line widths and column densities of HI, CIV and SiIV ions based on Voigt profile fitting analysis of ~170 QSO spectra from publicly archived Keck Observatory Database of Ionized Absorption toward Quasars (KODIAQ) and the Ultraviolet and Visual Echelle Spectrograph (UVES) Spectral Quasar Absorption Database (SQUAD). The quasars span the epoch when the cosmic star formation rate triples between z ~ 4 and z ~ 2, and when helium reionization heats the IGM significantly at z ~ 3. The PIs will use their results to test theoretical models of the temperature-density relation of the CGM and the evolution of gas temperature and turbulence of the IGM/CGM at high redshifts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在早期宇宙中，星系际介质（IGM）主要充满了弥漫的氢气和氦气。IGM分布在一个由片和丝组成的宇宙网络中，被空隙隔开。星系团形成于这些结构的交叉点，并由IGM气体供给，这些气体落在被称为环星系介质（CGM）的星系周围区域。首席研究员Kim和Wakker将分析档案数据，以研究IGM的气体吸积和CGM中的星系外流之间的复杂相互作用，CGM控制着星星形成效率并介导星系演化。为了扩大参与，PI将组织一系列与研究相关的公开讲座，并通过威斯康星州空间大学开发一个在线展览。PI还将继续与当地初中和高中合作，以增加学生参加一年一度的科学奥林匹克锦标赛。PI将通过确定HI的吸收线宽和柱密度来估计2 z4处漫射CGM/IGM的温度和湍流，CIV和SiIV离子基于对公开存档的凯克天文台类星体电离吸收数据库中~170个类星体光谱的Voigt轮廓拟合分析（KODIAQ）和紫外和可见中阶梯光谱仪（UVES）光谱类星体吸收数据库（SQUAD）。类星体跨越了宇宙星星形成速率在z ~ 4和z ~ 2之间增加三倍的时期，以及氦再电离在z ~ 3处显著加热IGM的时期。PI将使用他们的结果来测试CGM的温度-密度关系的理论模型和IGM/CGM在高红移下的气体温度和湍流的演变。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估而被认为值得支持。