Abstract
We performed a series of 29 gasdynamical simulations of disc galaxies, barred
and unbarred, with various stellar masses, to study the impact of the bar on
star formation history. Unbarred galaxies evolve very smoothly, with a star
formation rate (SFR) that varies by at most a factor of three over a period of
2 Gyr. The evolution of barred galaxies is much more irregular, especially at
high stellar masses. In these galaxies, the bar drives a substantial amount of
gas toward the centre, resulting in a high SFR, and producing a starburst in
the most massive galaxies. Most of the gas is converted into stars, and gas
exhaustion leads to a rapid drop of star formation after the starburst. In
massive barred galaxies (stellar mass M* > 2x10^10 Msun) the large amount of
gas funnelled toward the centre is completely consumed by the starburst, while
in lower-mass barred galaxies it is only partially consumed. Gas concentration
is thus higher in lower-mass barred galaxies than it is in higher-mass ones.
Even though unbarred galaxies funnelled less gas toward their centre, the lower
SFR allows this gas to accumulate. At late times, the star formation efficiency
is higher in barred galaxies than unbarred ones, enabling these galaxies to
maintain a higher SFR with a smaller gas supply. Several properties, such as
the global SFR, central SFR, or central gas concentration, vary monotonically
with time for unbarred galaxies, but not for barred galaxies. Therefore one
must be careful when comparing barred and unbarred galaxies that share one
observational property, since these galaxies might be at very different stages
of their respective evolution.
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