The Time Variability and Duty Cycle of Active Galactic Nuclei During Quenching

淬火过程中活动星系核的时间变化和占空比

• 批准号: 2307375
• 负责人: Katheryn French
• 金额: $ 33.8万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307375&HistoricalAwards=false
• 关键词: Time; Variability; Duty; Cycle; Active

Galaxies like the Milky Way are steadily forming stars, yet such galaxies will eventually end star formation and "quench". The physical drivers of how star formation ends in galaxies are not well understood, but the supermassive black holes that are found in the centers of massive galaxies may play a key role. The project will use tracers of time-variable emission from the areas illuminated by central supermassive black holes in galaxies to study the impact on galaxies which have recently ended star formation. The project will provide crucial context for understanding the galaxies discovered at larger distances with current and near-future facilities such as JWST, 20-40 meter ground-based telescopes, and the next-generation Very Large Array (ngVLA). The project includes time spent developing and implementing programs for the University of Illinois Astronomy summer camp. This camp is aimed at girls in grades 10-12, though students of any gender can apply. We will design and implement activities for students to explore the changing sky with time-series data to explore goal-setting methods.The evolution of galaxies from star-forming to quiescent is fundamental to the build-up of the observed galaxy population. There is growing evidence that many galaxies, especially at high redshift, experience this transition during a period of rapid change. Feedback from Active Galactic Nuclei (AGN) can provide enough energy to end star formation, yet the role of AGN activity and the mechanisms by which it can end star formation remain uncertain. We propose to use post-starburst galaxies identified at low redshift as laboratories for studying how and when AGN feedback might act. These galaxies have experienced recent bursts of star formation that have ended suddenly within the last billion years, analogous to the dramatic quenching seen in high redshift massive quiescent galaxies. AGN activity is difficult to measure during the post-starburst phase due to the uncertain nature of many commonly-used AGN tracers as well as the inherent variability of AGN. The PIs will study the presence of AGN activity during the post-starburst phase using tracers sensitive to a range of timescales. They will use archival and targeted optical and radio observations to study optical variability on timescales of weeks-years, radio variability on timescales of years-decades, and extreme changes in state over periods of 10,000-100,000 years using extended ionized regions. Their results will provide crucial context for future observations of higher redshift evolving galaxies, for which the community will soon obtain deep rest-frame optical spectroscopy with JWST and 20-40m ground-based telescopes, and cold molecular gas measurements with the ngVLA. Utilizing time-domain observations in multiple wavelengths will allow the field of galaxy evolution to maximize the scientific return on the investment in time domain astrophysics recommended in the Astro2020 decadal survey report.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.

像银河系这样的星系正在稳步形成恒星，但是这样的星系最终将结束星形形成和“淬火”。恒星形成如何在星系结束的物理驱动器尚不清楚，但是在大型星系中心发现的超大质量黑洞可能起关键作用。该项目将使用星系中央超级质量黑洞照亮区域的时间变化排放的示踪剂来研究对最近结束恒星形成的星系的影响。该项目将提供至关重要的环境，以了解在较大的距离内发现的星系，并使用当前和近距离设施，例如JWST，20-40米的地面望远镜，以及下一代非常大的阵列（NGVLA）。该项目包括为伊利诺伊大学天文学夏令营制定和实施计划的时间。该营地针对10 - 12年级的女孩，尽管任何性别的学生都可以适用。我们将设计和实施活动的活动，以供学生探索不断变化的天空，以探索目标设定方法。星系从恒星形成到静态的演变对于观察到的星系人群的积累至关重要。越来越多的证据表明，许多星系，尤其是在高红移时，在快速变化时期经历了这种过渡。活性银河核（AGN）的反馈可以提供足够的能量来结束恒星形成，但是AGN活性的作用和它可以结束恒星形成的机制仍然不确定。我们建议使用在低红移时确定的季后赛星系作为研究AGN反馈如何以及何时可能采取行动的实验室。这些星系最近经历了恒星形成的爆发，在过去的十亿年内突然结束了，类似于在高红移巨大的静态星系中看到的戏剧性淬火。由于许多常用AGN示踪剂的不确定性质以及AGN的固有变异性，因此在饥饿后阶段很难测量AGN活性。 PI将使用对一系列时间尺度敏感的示踪剂在恒星后期研究AGN活性的存在。他们将使用档案和针对性的光学和无线电观测值来研究数周年尺度的光学变异性，多年来时间尺度的无线电变异性以及使用扩展的电离区域的10,000-100，000年期间状态的极端变化。他们的结果将为未来对红移不断发展的星系的观察提供至关重要的环境，为此，社区将很快通过JWST和20-40M地面望远镜获得深层的静止光谱光谱，并使用NGVLA获得冷分子气体测量。在多个波长中利用时间域的观察将使银河发展领域最大化Astro2020 DeCadal调查报告中建议的对时域天体物理学的科学投资回报。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识优点和广泛的crietia crietia criperia criperia criperia criperia cripitia criperia criperia criperia cribitia criperia criperia criperia cripitia criperia cripitia cristia cripitia rection recteria rection this奖项。