Looking Out for the Little Guy: A Comprehensive Study of Star Formation in Dwarf Galaxies

寻找小家伙：矮星系恒星形成的综合研究

• 批准号: 1813871
• 负责人: Alyson Brooks
• 金额: $ 28.06万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1813871&HistoricalAwards=false
• 关键词: Looking; Out; Little; Guy; Comprehensive

In 2010, the Large Synoptic Survey Telescope (LSST) was named the top-ranked ground-based astronomy project for the coming decade. The telescope will begin gathering light in 2019, and begin a full survey of the visible sky two years later. The survey will discover billions of new astronomical objects, including hundreds of new galaxies nearby to our own Milky Way galaxy. The new galaxies that we will discover are so faint that they could not be found by previous telescopes. These tiny galaxies are also ideal places to test fundamental questions about the origin of galaxies in our Universe. This research focuses on the fact that these tiny galaxies are very sensitive to the first stars that formed in our Universe. This fact has not been sufficiently explored in previous research. To prepare astronomers to understand what these galaxies tell us about the origins of our Universe, this research focuses on three key areas. First, they will predict the number of faint galaxies that the National Science Foundation's LSST should discover. Second, they will predict how far away from the Milky Way the LSST might find the faint galaxies. Third, they will predict whether any of these galaxies is still forming stars today, or whether they all stopped forming stars billions of years ago. The research advances the scientific leadership of the United States and help to safeguard the United States' investment in LSST. The project focuses on training students who are first-generation college students, with the goal of diversifying the US technical workforce. An expanded and diversified scientific workforce helps to ensure that the US remains a leader in innovation and economic growth.The LSST will revolutionize our knowledge of dwarf galaxies, especially in the ultra-faint regime. However, simulators have barely begun to extend their successful models to stellar masses below 1 million solar masses. Now is the critical time to understand whether our current simulations can continue to explain galaxy formation down into the ultra-faint range, or whether a new understanding of star formation in low mass dark matter halos will be required. The goal of this work is to gain substantial knowledge about the processes that control early star formation in dwarf galaxies and subsequent quenching. The number of observed galaxies with stellar masses below 10 thousand solar masses depends strongly on the density of gas from which the first stars could form in the early Universe. The proposed work will generate hundreds of simulated dwarf galaxies, with stellar masses ranging from one billion solar masses (roughly 1/10 the mass of the Milky Way) down to 1000 solar masses in the range of ultra-faint dwarf galaxies. This work utilizes the simulations to (1) pinpoint the role of star formation density threshold on the number of galaxies that form, and the resulting stellar mass function; (2) make predictions for the number of ultra-faint dwarf galaxies as function of radius from the Milky Way; (3) study the processes that quench dwarf galaxies as function of mass and environment, and make predictions for the quenched fraction in the field that can be observed by future facilities. This work also establishes a program to support and mentor first-generation college students (many of whom are likely to also be from groups historically underrepresented in STEM) as they transition to being undergraduates. The program will (1) develop a mentoring relationship between students and members of the Rutgers Physics & Astronomy department, (2) utilize cohort building activities to develop the students into a peer support network for each other, (3) introduce the students to basic research tools and get them involved in original research. These three goals have been shown to increase the retention of underrepresented students in science. The overall aim is to improve the demographic diversity of both the Rutgers Physics & Astronomy undergraduate majors, but also of the Physics and Astronomy community. This program will also train graduate students to teach and mentor the first-year students, and educate the graduate student mentors on issues of equity and barriers to education that first-year/underrepresented students face.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.

2010年，大型综合巡天望远镜（LSST）被评为未来十年排名第一的地基天文学项目。 该望远镜将于2019年开始收集光线，两年后开始对可见天空进行全面调查。 这项调查将发现数十亿个新的天文物体，包括我们银河系附近的数百个新星系。 我们将发现的新星系是如此微弱，以至于以前的望远镜无法发现它们。 这些微小的星系也是测试我们宇宙中星系起源的基本问题的理想场所。 这项研究的重点是这些微小的星系对我们宇宙中形成的第一批恒星非常敏感。 这一事实在以前的研究中没有得到充分的探讨。 为了让天文学家了解这些星系告诉我们关于宇宙起源的信息，这项研究集中在三个关键领域。 首先，他们将预测美国国家科学基金会的LSST应该发现的暗淡星系的数量。 其次，他们将预测LSST可能会在距离银河系多远的地方找到这些暗淡的星系。 第三，他们将预测这些星系中是否有任何一个今天仍在形成恒星，或者它们是否在数十亿年前就停止形成恒星。该研究推动了美国的科学领导地位，并有助于保护美国在LSST上的投资。 该项目的重点是培养第一代大学生，目标是使美国技术劳动力多样化。 扩大和多样化的科学工作队伍有助于确保美国在创新和经济增长方面保持领先地位。LSST将彻底改变我们对矮星系的认识，特别是在超微弱区域。 然而，模拟器几乎没有开始将其成功的模型扩展到100万太阳质量以下的恒星。 现在是了解我们目前的模拟是否可以继续解释星系形成到超微弱范围的关键时刻，或者是否需要对低质量暗物质晕中的星星形成进行新的理解。这项工作的目标是获得有关控制矮星系中早期星星形成和随后淬灭的过程的实质性知识。观测到的恒星质量低于1万太阳质量的星系数量在很大程度上取决于早期宇宙中第一批恒星形成的气体密度。拟议的工作将产生数百个模拟矮星系，恒星质量从10亿太阳质量（大约是银河系质量的1/10）到1000太阳质量的超微弱矮星系。 本工作利用模拟结果（1）确定了星星形成密度阈值对形成星系数量的影响，以及由此得到的恒星质量函数：（2）预测了超暗矮星系数量与银河系半径的关系;（3）研究矮星系的猝灭过程与质量和环境的关系，并对未来设施可以观测到的现场淬火分数进行预测。 这项工作还建立了一个计划，以支持和指导第一代大学生（其中许多人可能也来自STEM历史上代表性不足的群体），因为他们过渡到本科生。该计划将（1）发展学生和罗格斯大学物理天文学系成员之间的指导关系，（2）利用队列建设活动，将学生发展成为彼此的同伴支持网络，（3）向学生介绍基础研究工具，并让他们参与原创研究。这三个目标已被证明可以提高科学领域代表性不足的学生的保留率。总体目标是提高罗格斯大学物理天文学本科专业的人口多样性，以及物理和天文学社区的人口多样性。该项目还将培养研究生对一年级学生的教学和指导，并就一年级/代表性不足的学生面临的平等问题和教育障碍对研究生导师进行教育。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Dancing in the Dark: Uncertainty in Ultrafaint Dwarf Galaxy Predictions from Cosmological Simulations

• DOI: 10.3847/1538-4357/ab0085
• 发表时间: 2018-10
• 期刊: The Astrophysical Journal
• 作者: F. Munshi;A. Brooks;C. Christensen;Elaad Applebaum;K. Holley-Bockelmann;T. Quinn;J. Wadsley

Ultrafaint Dwarfs in a Milky Way Context: Introducing the Mint Condition DC Justice League Simulations

• DOI: 10.3847/1538-4357/abcafa
• 发表时间: 2020-08
• 期刊: The Astrophysical Journal
• 作者: Elaad Applebaum;A. Brooks;C. Christensen;F. Munshi;T. Quinn;S. Shen;M. Tremmel

Quantifying Scatter in Galaxy Formation at the Lowest Masses

• DOI: 10.3847/1538-4357/ac0db6
• 发表时间: 2021-01
• 期刊: The Astrophysical Journal
• 作者: F. Munshi;A. Brooks;Elaad Applebaum;C. Christensen;T. Quinn;Serena K Sligh

A stochastically sampled IMF alters the stellar content of simulated dwarf galaxies

随机采样的 IMF 改变了模拟矮星系的恒星含量

• DOI: 10.1093/mnras/stz3331
• 发表时间: 2019
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Applebaum, Elaad;Brooks, Alyson M.;Quinn, Thomas R.;Christensen, Charlotte R.
• 通讯作者: Christensen, Charlotte R.