The Triggering and Quenching of Star-Formation and Nuclear Activity in Galaxies

斯隆数字巡天（Sloan Digital Sky Survey）等对局部宇宙的星系调查表明，星系分为两大类：蓝色的、形成恒星的盘状星系和红色的、静止的球状或早期型星系。在邻近的宇宙中，最明亮、质量最大的星系是静止的，它们优先出现在密集的环境中，比如星系群和星系团。相比之下，形成恒星的星系具有较低的恒星质量和低密度的环境。天文学家还知道，几十亿年前宇宙中的恒星形成要活跃得多。这项研究将回答的关键问题如下：从早期到现在，是什么物理过程抑制了恒星形成和核活动？该奖项将为下一阶段的大尺度环境红移演化观测（ORELSE）星系调查提供支持。这包括利用凯克10米望远镜上的多目标红外探测光谱仪（MOSFIRE）进行全面的近红外光谱调查，以及多波长（x射线、无线电和红外）观测。通过与ORELSE提供的当地和全球环境的精确测量相关联，该计划将确定气体燃料和淬火事件的原因和影响，这些事件推动了星系在30亿年的关键时期内的演化，而恒星形成和核活动正在迅速下降。该奖项还将通过支持加州大学戴维斯分校物理和数学科学本科生研究参与者指导计划（MURPPS）来扩大代表性不足的学生基础。该计划将使参与MURPPS的未被充分代表的学生人数增加30%以上，并与NSF的承诺直接一致，即实现妇女、残疾人和未被充分代表的少数民族在STEM领域的充分参与。

Galaxy surveys in the local universe such as the Sloan Digital Sky Survey have shown that galaxies populate two broad categories: blue, star-forming disk galaxies and red, quiescent spheroidal or early-type galaxies. In the nearby universe, the most luminous and massive galaxies are quiescent, and they are preferentially found in dense environments, such as groups and clusters. In contrast, star-forming galaxies have lower stellar masses and occupy low-density environments. Astronomers also know that star-formation in the universe was significantly more active several billion years ago. The key question that will be answered by this research is the following: what physical processes drive the suppression of star formation and nuclear activity between early times and the present day.This award will enable for the next phase of the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey of galaxies. This includes a comprehensive, near-IR spectroscopic survey with the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on the Keck 10-m telescope, together with multi-wavelength (X-ray, radio, and infrared) observations. By correlating with the precise measures of local and global environment afforded by ORELSE, the program will determine the cause and effect of gas-fueling and quenching events that drive galaxy evolution over a critical 3-billion year period where star formation and nuclear activity are rapidly declining.This award will also expand the underrepresented student base by supporting the Mentorship for Undergraduate Research Participants in Physical and Mathematical Sciences (MURPPS) program at the University of California-Davis. The program will increase the number of underrepresented students who can participate in MURPPS by over 30% and is directly aligned with the NSF's commitment to achieve full participation of women, persons with disabilities, and underrepresented minorities in STEM fields.