Cool Galactic Winds and Gas Accretion: Joint Constraints from Integral Field Spectroscopy and Pencil Beam Probes

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Astronomers seek to understand how diffuse gas throughout the Universe formed into galaxies. Under the influence of gravity alone, all this gas should have collapsed into stars. However, most of the matter in the Universe is not in stars; it is diffuse gas. Furthermore, galaxies rarely show gas falling in; it is almost always flowing out. Study of diffuse gas around galaxies is needed to understand how some small fraction of this tenuous vapor finally gave rise to the universe we know today. In this project, Rubin and collaborators take advantage of new observations of hundreds of galaxies that reveal nearby gas. Their specialized methods are sensitive to cool gas, which is relatively massive and dense. They can image its position and determine its velocity relative to each galaxy. The result will be a large sample of galaxies and gas flows to provide new constraints for theoretical models. The PI will recruit and train undergraduates from underserved populations to participate in the analysis. Suitable projects that fit into the overall research plan have been defined. These projects make use of modern, inquiry-based teaching methods. This project will draw upon data from the ongoing Sloan Digital Sky Survey / Mapping Nearby Galaxies at APO (MaNGA) initiative, which has obtained integral field unit (IFU) spectroscopy of several thousand nearby galaxies. Rubin and collaborators will study cold, neutral gas via the Na I transition, which is accessible to ground-based, optical spectroscopy. They will form two dimensional velocity maps of this gas and compare them to broadband imaging of each galaxy. These data will be augmented with a complementary study of Ca II and Na I absorption spectroscopy of a sample of galaxies with fortuitously aligned, background-illuminating quasars. This complementary investigation will be performed using Keck telescope observations, for which partial time has already been awarded. Together, these investigations will provide a census of the incidence, morphology, and mass of gas inflows. They will also address whether large-scale outflows can be linked to intrinsic galaxy properties and orientation and whether supernova ejecta can plausibly drive the momentum of such outflows. Undergraduates will be recruited from San Diego State University, a federally designated Hispanic Serving Institution. Undergraduate research projects will include generating a publishable catalog of Keck spectroscopy, and analysis of MaNGA derived gas flow morphology and kinematics.