The Imprint of Galaxy Formation on the Intergalactic Environment

星系形成对星系际环境的影响

• 批准号: 0908910
• 负责人: Piero Madau
• 金额: $ 55.15万
• 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: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0908910&HistoricalAwards=false
• 关键词: Imprint; Galaxy; Formation; Intergalactic; Environment

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr. Madau and his team will combine observations of the gas from which the galaxies were formed with theoretical and numerical studies of the state of that gas. The intergalactic gas is ionized by the ultraviolet light from short-lived massive stars and from the active nuclei of galaxies, so the amount of neutral gas tells us about past star formation, and about the black holes that lie at the centers of galaxies and power their active nuclei. To set limits on this ionizing light at times when the cosmos had expanded only to a quarter of its present size, the team will examine the spectra of quasars dating from this period, and make a census of the deep absorption lines of neutral hydrogen in their light. They will take infrared spectra of even more distant quasars to measure the absorption lines of heavier elements that are produced in stellar interiors, to examine how rapidly these were produced from stars and flung into the intergalactic gas. By looking at spectra of pairs of quasars that are nearby on the sky, the team will study gas around the nearer quasar by its absorption of the light of the more distant object. The team will improve CUBA, a one-dimensional radiative transfer code, and release it to the public. This code will be used to trace ionizing photons as they propagate through models of the cosmos that follow both the invisible dark matter and the gas, as gas condenses into star-forming galaxies. These calculations will also consider the effect of galactic winds in blowing the metals formed in the stars out into the intergalactic gas. A graduate student and a postdoc will be trained by participating in the research. Team members expect to mentor undergraduate researchers, and to take part in a summer program for talented undergraduates from low-income families. The upgraded CUBA code will be released to the astronomical community, and visualizations from the simulation runs will be available for public outreach.

该奖项由 2009 年美国复苏和再投资法案（公法 111-5）资助。马道和他的团队将对形成星系的气体的观测与对该气体状态的理论和数值研究结合起来。 星系际气体被来自短命大质量恒星和活跃星系核的紫外线电离，因此中性气体的数量告诉我们过去恒星的形成，以及位于星系和能量中心的黑洞他们的活性核。 为了在宇宙仅膨胀到目前大小的四分之一时对这种电离光进行限制，研究小组将检查这一时期类星体的光谱，并对它们中的中性氢的深吸收线进行普查。光。 他们将利用更遥远的类星体的红外光谱来测量恒星内部产生的较重元素的吸收线，以检查这些元素从恒星产生并抛入星系间气体的速度有多快。 通过观察天空中附近的成对类星体的光谱，研究小组将通过吸收较远物体的光来研究较近类星体周围的气体。 该团队将完善一维辐射传输代码CUBA，并向公众发布。 当气体凝结成恒星形成星系时，该代码将用于追踪电离光子在宇宙模型中传播时跟随不可见的暗物质和气体的情况。 这些计算还将考虑银河风将恒星中形成的金属吹入星系间气体的影响。 一名研究生和一名博士后将通过参与该研究接受培训。 团队成员希望指导本科生研究人员，并参加针对来自低收入家庭的优秀本科生的暑期项目。 升级后的 CUBA 代码将发布给天文学界，模拟运行的可视化结果将可供公众推广。