LYRA: Dwarf galaxies on small scales in a cosmological context

Thales Gutcke (Princeton University)

May 13, 2022

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Abstract: Dwarf galaxies (Mstar < 1e8 Msun) are increasingly becoming an area of interest, not only for Local Group studies and for dark matter profiles but also as contributors to reionization and the chemical enrichment of the inter-galactic medium (IGM). With the prospect of deeper observations of local systems and increasing numbers of detections at higher redshift, it is highly timely to advance our theoretical understanding of the formation of dwarf galaxies, including the relatively small-scale processes of star formation (SF) and feedback that govern their evolution. Unfortunately, the baryons that comprise the interstellar medium (ISM) in cosmological simulations are typically modeled with effective (sub-grid) models that prevent the self-consistent formation of giant molecular clouds. I will present LYRA, a novel galaxy formation model that reaches a critical scale where individual SNe can be resolved without depending on a feedback efficiency parameter, which has long been a major source of uncertainty in such models. I will show that LYRA galaxies match the stellar mass, size, stellar kinematics and metallicity relations of Local Group dwarf galaxies well. Then I will present predictions concerning dwarf galaxy substructure and the high-z contamination of the IGM.