Doctor of Philosophy, The Ohio State University, 2024, Physics

Stellar clusters form inside large clouds of gas, which collapse under gravity until the feedback from the newly formed stars begins to push the gas away, disrupting further star formation. In this dissertation we explore several of the feedback mechanisms responsible for stopping star formation. We will look in depth at two mechanisms in particular: Radiation pressure and cosmic ray diffusion. To analyze these pressures, we build simple models which we then expand. Radiation pressure's role depends greatly on the composition of the dust embedded in the gas the stars form from. The dust interacts with the photons from the star cluster, scattering and absorbing them, before re-radiating the photons in the infra-red. To build a more realistic model of radiation pressure, we use time dependent spectral data from simulations and realistic dust grain distributions and optical properties. The effects of cosmic ray diffusion are controlled by several parameters, such as the diffusion coefficient and the size scale of the shell of material the cosmic rays are acting on. We compare cosmic ray pressure to radiation pressure, and the pressure from hot ionized gas around the stellar cluster. We also apply our analysis of each of these pressures to observations. We do this to estimate the role of each pressure in observed regions, helping to explore the mechanisms which govern the star formation rates in star-forming regions of galaxies. Additionally, we analyze the dynamics of shells driven by radiation pressure, cosmic ray diffusion, and the pressure from hot ionized gas. From these simple dynamical models we draw conclusions about the roles of each of the pressures, and examine the parameter space where each dominates. We find that radiation pressure is highly important to the initial stages of feedback, dominating the other studied pressures for the youngest and most compact clusters. Radiation pressure can rapidly drive gas away from the central star cluster, (open full item for complete abstract)

Committee: Todd Thompson (Advisor); Andrew Heckler (Committee Member); Joanne Patterson (Committee Member); Adam Leroy (Committee Member); Christopher Hirata (Committee Member) Subjects: Astronomy; Astrophysics; Physics