A New View of the Chemical Evolution of Nearby Galaxies with Keck and VLT Integral Field Spectroscopy

随着恒星的演化，它们产生并将重元素（即比氦重的元素）分布到星际气体中。随着时间的推移，星系中的重元素含量不断增加，增加了气体的金属丰度。金属丰度在控制星系如何形成新恒星方面起着重要作用。金属丰度也会发生变化，因为来自星系周围的气体流入，以及由恒星形成的剧烈爆发引起的星系盘气体流出。一旦进入星系，具有不同金属丰度的气体就会因湍流和流动而混合在一起。因此，星系中局部的金属丰度反映了所有这些因素之间的竞争。这些研究人员将研究邻近星系中金属丰度的区域间变化，以了解这些重要过程如何塑造星系的重元素含量。PI还将领导一个专业发展和指导项目，为即将转到加州大学圣地亚哥分校物理科学专业的学生提供指导，目的是增加他们对本科研究的参与。研究人员将利用凯克宇宙网成像仪（KCWI）和甚大望远镜多单元光谱探测器（VLT-MUSE）进行的新的积分场光谱观测，在测量附近星系的ISM金属丰度方面迈出关键的下一步。这些仪器将获得3500-9300埃光谱的高灵敏度全采样图，允许使用对氧、氮和硫的温度敏感的极光发射线进行详细的金属丰度研究。由于准确诊断金属丰度所需的光谱线模糊，以往的研究在评估金属丰度方面受到限制。研究人员将使用KCWI和MUSE的观测结果来研究金属丰度不均匀性作为星系特性的函数，如形态、特定恒星形成率和恒星条的存在，他们将把这些观测结果与星系模拟和理论的预测进行比较。为了扩大对科学的参与，PI将为加州大学圣地亚哥分校物理科学专业的转学生举办一系列研讨会，以提供研究技能培训和寻找研究职位的指导。PI还将启动有组织的数据收集，以跟踪转学生的职业道路。该数据集将用于评估该计划的有效性，并制定进一步的策略，以增加未被充分代表的少数民族攻读物理科学高级学位的比例。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

As stars evolve, they produce and distribute heavy elements (i.e. elements heavier than helium) into the interstellar gas. Over time, the heavy element content builds up in a galaxy, increasing the metallicity of the gas. Metallicity has an important role in governing how galaxies form new stars. Metallicity can also change because of inflow of gas from the galaxy's surroundings and outflows of gas from the galaxy disk caused by intense bursts of star formation. Once it is in a galaxy, gas with varying metallicity is mixed together by turbulence and flows. The local metallicity in a galaxy therefore reflects the competition between all of these factors. These investigators will study the region-to-region variation of metallicity in nearby galaxies to learn about how these important processes shape the heavy element content of galaxies. The PI will also lead a program of professional development and mentoring for incoming transfer students to the physical sciences at UC San Diego with the goal of increasing their participation in undergraduate research. The investigators will make the next critical step forward in measuring ISM metallicities in nearby galaxies using new integral field spectroscopic observations performed with the Keck Cosmic Web Imager (KCWI) and the Very Large Telescope Multi-Unit Spectroscopic Explorer (VLT-MUSE). These instruments will obtain high sensitivity, fully-sampled maps of the 3500-9300 Angstrom optical spectrum allowing detailed metallicity studies using temperature-sensitive auroral emission lines of oxygen, nitrogen and sulfur. Previous studies have been limited in their assessment of metallicity due the faintness of the spectral lines needed for accurate metallicity diagnostics. The investigators will use the KCWI and MUSE observations to study metallicity inhomogeneity as a function of galaxy properties such as morphology, specific star formation rate and presence of a stellar bar and they will compare these observations to predictions from galaxy simulations and theory. To broaden participation in science, the PI will lead a series of workshops for transfer students in the physical sciences at UC San Diego to provide training in research skills and guidance in finding research positions. The PI will also initiate organized data collection to track the career path of transfer students. This dataset will be used to assess the effectiveness of the program and develop further strategies for increasing the fraction of underrepresented minorities who pursue advanced degrees in the physical sciences.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.