The Physics of Satellite Galaxy Quenching: Novel Analysis of Observations, and High-Resolution Simulations

该项目将研究阻止卫星星系中恒星形成的物理机制。这些围绕更多大质量星系运行的星系占全球星系总数的很大一部分。人们对它们知之甚少。这项拟议的研究将结合对成像和光谱数据集的分析以及计算机模拟来研究这些卫星星系中恒星形成猝灭的物理机制。作为新的加州桥计划的一部分，库珀博士还将教育和指导代表人数不足的学生，该计划旨在增加从加州州立大学成功过渡到加州大学天体物理或物理研究生院的少数族裔学生的数量。作为该计划的核心成员，库珀博士将为加州大学桥学院的个别学者提供一对一的指导和研究顾问，同时还将举办为期一天的专业发展研讨会，重点讨论从科学编码到准备GRE考试的各种主题。尽管现代星系形成模型成功地模拟了大质量星系在宇宙时间内的演化，但现代的星系形成模型无法再现低质量星系在宇宙时间内的特性。我们的理论图景中的这一缺陷在很大程度上是由于无法理解卫星(或“环境”)猝灭的物理学。为了解决这一缺点，拟议的研究计划采用了对恒星质量和宿主晕质量在z2的大范围内的卫星星系的观测，同时进行了集中的半解析建模工作，以确定一旦卫星被吸积到宿主晕上时所起作用的特殊物理机制。拟议的分析将测试一个模型，在该模型中，饥饿和冲压剥离分别在临界规模以上和之下是主要的淬火机制。库珀博士将领导一项有针对性的光谱活动，对一组史无前例的z~1卫星星系样本进行分类。此外，还将对z~2的卫星进行统计分析，利用遗留下来的河外区域进行深度成像。这一计划将极大地扩展我们对物理过程的了解，这些过程使卫星熄灭，并推动在z2静止的星系群的建立，直接解决了当前星系形成模型的一个重大失败。此外，作为新的加州桥计划的一部分，库珀博士将教育和指导未被充分代表的学生，该计划旨在增加从加州州立大学成功过渡到加州大学天体物理或物理研究生院的少数族裔学生的数量。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project will study the physical mechanisms responsible for halting the formation of stars in satellite galaxies. These galaxies, which orbit more massive galaxies, represent a large segment of the global galaxy population. They are poorly understood. The proposed research will combine analysis of imaging and spectroscopic datasets as well as computer simulations to study the physical mechanism for quenching of star formation in these satellite galaxies. Dr. Cooper will also educate and mentor underrepresented students as part of the new Cal-Bridge program, which is designed to increase the number of minority students who successfully transition from Cal State Universities into graduate school at UC campuses in astrophysics or physics. As a core member of the program, Dr. Cooper will serve as a one-on-one mentor and research advisor to individual Cal-Bridge scholars, while also developing day-long, program-wide professional development seminars, focusing on topics ranging from scientific coding to preparation for the GRE exam.Despite success at modeling the evolution of massive galaxies over cosmic time, modern models of galaxy formation fail to reproduce the properties of low-mass galaxies over cosmic time. This shortcoming in our theoretical picture is largely driven by an inability to understand the physics of satellite (or "environmental") quenching. To address this shortcoming, the proposed research program employs observations of satellite galaxies across a broad range in stellar mass and host halo mass at z 2 in tandem with a focused semi-analytic modeling effort, to identify the particular physical mechanisms at play once a satellite is accreted onto a host halo. The proposed analysis will test a model whereby starvation and ram-pressure stripping are the dominant quenching mechanisms above and below a critical scale, respectively. Dr. Cooper will lead a targeted spectroscopic campaign to catalog an unprecedented sample of satellite galaxies in groups at z ~ 1. This effort will be complemented by a statistical analysis of satellites at z 2 using deep imaging in legacy extragalactic fields. This program will significantly expand our knowledge of the physical processes that quench satellites and drive the build-up of the quiescent galaxy population at z 2, directly addressing a major failure of current galaxy formation models. In addition, Dr. Cooper will educate and mentor underrepresented students as part of the new Cal-Bridge program, which is designed to increase the number of minority students who successfully transition from Cal State Universities into graduate school at UC campuses in astrophysics or physics.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.