Collaborative Research: Spatially Resolving the Mechanisms of Star Formation Quenching Using Molecular Gas Observations

When we look deep into space with modern telescopes, the finite speed of light enables us to see galaxies as they appeared in the distant past. What we have learned from such observations is that most galaxies experience rapid star formation in their youth and declining star formation as they age. Still, there are wide variations in how quickly star formation stops, and we do not fully understand why the rate of star formation in galaxies changes. Have aging galaxies just run out of fuel, or has the fuel become unusable for some reason? One way to advance our knowledge is to make connections between the star formation rate and the cold hydrogen gas which is the fuel for star formation. The project investigators will take advantage of recently completed surveys of nearby galaxies, as well as state-of-the-art computer models, to pursue this goal. Through research experiences and mentoring, the project will expand pathways to scientific careers for students from minority backgrounds. The research experiences are designed for soldiers transitioning from the military to STEM fields. The team plans a wide variety of observations, including spatially resolved measurements of CO emission, which trace the molecular gas content, and optical integral field unit (IFU) spectroscopic surveys, which trace the young and old stellar populations. The investigators have merged their measurements into the Extragalactic Database for Galaxy Evolution (EDGE) and are now poised to extend these studies to galaxies with much lower gas content and star formation activity. They will conduct and analyze high-resolution simulations that match evolutionary scenarios to observational predictions, allowing factors such as galaxy structure and environment to be considered quantitatively. Among the key questions to be addressed are whether the cessation of star formation is driven largely by exhaustion of the available gas supply or by changes to the properties of the gas reservoir. 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.