Collaborative Research: Galactic Winds and the Multiphase Structure of the Circum-Galactic Medium

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Massive galaxies are embedded in a dynamic reservoir of particles and dark matter called the circumgalactic medium (CGM). The CGM not only represents a fossil record of galaxy formation, it also continues to shape their evolution through the interaction of cool infalling gas with outflows driven by stellar winds and supernovae. This research team will develop a state-of-the-art hydrodynamic galaxy simulation code to study the complex interplay between star formation induced outflows and the CGM. Synthetic UV absorption line spectra derived from these simulations will be directly compared with Hubble Space Telescope data to advance our understanding of the structure and dynamics of the CGM. These simulations will also be used in a program for pre-majors in science from underrepresented groups. The program will introduce them to the use of computer simulations in astrophysics and encourage them to consider a technically oriented major program of study. The research team will first incorporate the PhEW (Physically Evolved Winds) sub-grid model into the hydrodynamic galaxy simulation code ChaNGa and verify its accuracy. Once validated, they will begin modeling the CGM of current epoch Milky Way-like galaxies and begin making comparisons between the synthetic UV spectra with HST data. Through a series of such simulations that systematically explore a range of evolutionary paths, the team will try to assess which aspects of the CGM's absorption line properties are robust against galaxy history and which are more directly connected to star formation. Finally, the team will explore how CGM structure is affected by PhEW as a function of galaxy mass and environment by running a simulation that evolves galaxies within a cosmological volume (Romulus25; 25 Mpc sided cube). This will allow investigations of how the simulated HST/COS spectra vary as a function of galaxy type, mass, and environment and how the CGM evolves across these parameters.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.