AR 14307 (Archival Research)

Sun Jul 14 18:59:43 GMT 2024

Principal Investigator: Siang Oh
PI Institution: University of California - Santa Barbara
Investigators (xml)

Title: Turbulent Mixing and Thermal Instability in the Circumgalactic Medium
Cycle: 23

The cycle of baryons into and out of galaxies is a crucial link between cosmological scales and the fundamental processes of galaxy and star formation. However, only a small fraction of the baryons in the Universe resides as gas within galaxies -- much smaller than what theoretical models predict. Recent results with the Hubble Space Telescope suggest that a large fraction of the baryons that do not sit within galaxies still reside in their vicinity, in the so-called circumgalactic medium (CGM). Gas there arises both from cosmological infall and galactic winds. The goal of this proposed research is to carry out state-of-the-art idealized simulations with much more micro-physics (e.g. magnetic fields, thermal conduction, radiative cooling, turbulence) and higher resolution than cosmological simulations. We will explore the impact of hitherto neglected microphysical processes and formulate subgrid recipes for cosmological simulations. We focus on the following aspects: (i) Formation of cold gas: thermal instability in a turbulent medium; (ii) Survival of cold gas: the effects of magnetic draping; (iii) Non-thermal pressure support in cold gas; (iv) Formation of warm OVI gas: turbulent mixing and conduction; (v) Effectiveness of metal mixing; size of metal blobs. The results of this research will advance our understanding of the life cycle of baryons, and shed light on key questions at the nexus of cosmology, galaxy, and star formation. It will provide important theoretical interpretation of HST/COS spectra of absorption line systems in the CGM.