Presentation Archive

How stellar feedback regulates galactic star formation rates?

Chang-Goo Kim (Princeton)

May 05, 2022

Abstract: The importance of star formation feedback to the energetics of the interstellar medium (ISM) has been appreciated throughout the modern history of astronomy. Star formation is inefficient in gas consumption because feedback efficiently maintains the pressure support, which is otherwise rapidly lost via cooling and turbulence dissipation. At the same time, collective actions of feedback drive galactic-scale outflows, controlling the baryonic cycles of galaxies and beyond. Feedback is thus central to galaxy formation theory as well. To approach this multi-scale, multi-physics problem, I developed a numerical framework called TIGRESS, solving magnetohydrodynamics equations with gravity, star formation, and feedback in a local shearing box representing a patch of galactic disks. TIGRESS resolves the energy-conserving stage of most supernovae and includes the self-consistent variation of radiative heating by FUV. I use a suite of TIGRESS simulations surveying a large parameter space to quantify the role of feedback in setting ISM energy density (pressure) and hence star formation rates. I will then show a new way of characterizing multiphase galactic outflows using the joint probability density functions of outflow velocity and sound speed. Finally, I will introduce an ongoing effort to implement new subgrid models for more predictive galaxy formation simulations and the new TIGRESS extension with explicit UV radiation transfer and photochemistry module for more self-consistent cooling and heating in the multiphase ISM.