HI discs of L_∗ galaxies as probes of the baryonic physics of galaxy evolution
arxiv(2023)
摘要
Understanding what shapes the cold gas component of galaxies, which both
provides the fuel for star formation and is strongly affected by the subsequent
stellar feedback, is a crucial step towards a better understanding of galaxy
evolution. Here, we analyse the HI properties of a sample of 46 Milky Way
halo-mass galaxies, drawn from cosmological simulations (EMP-Pathfinder and
FIREbox). This set of simulations comprises galaxies evolved self-consistently
across cosmic time with different baryonic sub-grid physics: three different
star formation models [constant star formation efficiency (SFE) with different
star formation eligibility criteria, and an environmentally-dependent,
turbulence-based SFE] and two different feedback prescriptions, where only one
sub-sample includes early stellar feedback. We use these simulations to assess
the impact of different baryonic physics on the HI content of galaxies. We find
that the galaxy-wide HI properties agree with each other and with observations.
However, differences appear for small-scale properties. The thin HI discs
observed in the local Universe are only reproduced with a turbulence-dependent
SFE and/or early stellar feedback. Furthermore, we find that the morphology of
HI discs is particularly sensitive to the different physics models: galaxies
simulated with a turbulence-based SFE have discs that are smoother and more
rotationally symmetric, compared to those simulated with a constant SFE;
galaxies simulated with early stellar feedback have more regular discs than
supernova-feedback-only galaxies. We find that the rotational asymmetry of the
HI discs depends most strongly on the underlying physics model, making this a
promising observable for understanding the physics responsible for shaping the
interstellar medium of galaxies.
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