Laura Hunter, 2023
Title: Timescales of Stellar Feedback Driven Turbulence in the Interstellar Medium on Local Scales
Abstract: Stellar feedback --energy injected through stellar winds and supernovae-- drives the random motions of the gas in galaxies and can launch the gas out of galaxies as outflows. Turbulence driven by this stellar feedback from hot young stars is fundamental to modeling the evolution of galaxies. My dissertation research provides critical understanding of the timescales involved, constraining the impact of stellar feedback on the interstellar medium (ISM). My research determines these timescales by analysis of the lifetimes of young stars through star formation histories (SFH) along with the spatial distribution and kinematics of the atomic and ionized hydrogen gas of a large sample of nearby, star-forming, low-mass galaxies. To best understand the timescales involved, I focus on the local scales of the galaxies by connecting the recent formation of massive, young stars with turbulence in the ISM in 400 by 400 parsec regions. My dissertation research utilized multi-wavelength observations of the galaxies including radio data from the Very Large Array (VLA), optical spectroscopy from the WIYN 3.5m telescope, and optical photometry from the Hubble Space Telescope. From my work, I found no strong correlation between the ionized gas velocity dispersion and the star formation activity between 5-500 Myrs. However, I found a strong and repeated correlation between the atomic hydrogen turbulence measures and the star formation activity ~100 Myrs ago. This suggests the star formation activity and atomic gas are coupled on this timescale. The repeated correlation between star-formation activity approximately 100 Myrs ago, and the HI turbulence properties, may be related to the time scales over which turbulence decays in the ISM. Additionally, my research demonstrates a possible difference in the global and local turbulence properties of low-mass galaxies. This physical scale dependence may be related to what drives turbulence at different scales within the ISM.