Simulating nearby disc galaxies on the main star formation sequence I. Bar formation and the building of the central gas reservoir
arxiv(2024)
Abstract
Past studies have long emphasised the key role played by galactic stellar
bars in the context of disc secular evolution, via the redistribution of gas
and stars, the triggering of star formation, and the formation of prominent
structures such as rings and central mass concentrations. However, the exact
physical processes acting on those structures, as well as the timescales
associated with the building and consumption of central gas reservoirs are
still not well understood. We are building a suite of hydro-dynamical RAMSES
simulations of isolated, low-redshift galaxies that mimic the properties of the
PHANGS sample. The initial conditions of the models reproduce the observed
stellar mass, disc scale length, or gas fraction, and this paper presents a
first subset of these models. Most of our simulated galaxies develop a
prominent bar structure, which itself triggers central gas fuelling and the
building of an over-density with a typical scale of 100-1000 pc. We confirm
that if the host galaxy features an ellipsoidal component, the formation of the
bar and gas fuelling are delayed. We show that most of our simulations follow a
common time evolution, when accounting for mass scaling and the bar formation
time. In our simulations, the stellar mass of 10^10 M_⊙ seems to
mark a change in the phases describing the time evolution of the bar and its
impact on the interstellar medium. In massive discs (M_⋆≥
10^10 M_⊙), we observe the formation of a central gas reservoir with
star formation mostly occurring within a restricted starburst region, leading
to a gas depletion phase. Lower-mass systems (M_⋆ <
10^10 M_⊙) do not exhibit such a depletion phase, and show a more
homogeneous spread of star-forming regions along the bar structure, and do not
appear to host inner bar-driven discs or rings.
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