Differences in star formation activity between tidally triggered and
  isolated bars: a case study of NGC 4303 and NGC 3627
  Galactic bars are important drivers of galactic evolution, and yet how they
impact the interstellar medium and correspondingly star formation, remains
unclear. We present simulation results for two barred galaxies with different
formation mechanisms, bars formed in isolation or via a tidal interaction, to
consider the spatially and temporally varying trends of star formation. We
focus on the early (< 1Gyr) epoch of bar formation so that the interaction is
clearly identifiable. The nearby NGC 4303 (isolated) and NGC 3627 (interaction
history) are selected as observational analogues to tailor these simulations.
Regardless of formation mechanism, both models show similar internal dynamical
features, although the interaction appears to promote bar-arm disconnection in
the outer disc velocity structure. Both bars trigger similar boosts in star
formation (79%; 66%), while the interaction also triggers an earlier 31% burst.
Significant morphological dependence is observed in the relation between
surface gas and star formation rate. In both cases, the bar component is
notably steepest; the arm is similar to the overall disc average; and the
inter-arm clearly the shallowest. A distinguishable feature of the tidal disc
is the presence of moderately dense, inefficiently star forming gas mostly
confined to tidal debris outside the optical disc. The tidal disc also exhibits
a unique trend of radially increasing star formation efficiency and a clear
dearth of star formation which persists along the bar between the centre and
bar ends. These are potential signatures for identifying a barred system
post-interaction.
