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

University Of California-San Diego, La Jolla CA

Investigators

Abstract

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.