SDSS-IV MaNGA: Spatially resolved star formation in barred galaxies
  Bars inhabit the majority of local-Universe disk galaxies and may be
important drivers of galaxy evolution through the redistribution of gas and
angular momentum within disks. We investigate the star formation and gas
properties of bars in galaxies spanning a wide range of masses, environments,
and star formation rates using the MaNGA galaxy survey. Using a
robustly-defined sample of 684 barred galaxies, we find that fractional (or
scaled) bar length correlates with the host's offset from the star-formation
main sequence. Considering the morphology of the H$\alpha$ emission we separate
barred galaxies into different categories, including barred, ringed, and
central configurations, together with H$\alpha$ detected at the ends of a bar.
We find that only low-mass galaxies host star formation along their bars, and
that this is located predominantly at the leading edge of the bar itself. Our
results are supported by recent simulations of massive galaxies, which show
that the position of star formation within a bar is regulated by a combination
of shear forces, turbulence and gas flows. We conclude that the physical
properties of a bar are mostly governed by the existing stellar mass of the
host galaxy, but that they also play an important role in the galaxy's ongoing
star formation.
