Bars play an integral role in regulating star formation in spiral galaxies, from triggering central starbursts to driving quenching. The diverse star formation morphologies observed in local barred galaxies reflect different evolutionary stages of the bar. This makes studies of these stages essential for understanding how bars regulate star formation. In this context, we studied a sample of 12 nearby barred galaxies in the redshift range 0. 01 – 0. 06 to understand bar-driven quenching of star formation. These galaxies were identified as centrally quenched galaxies, that is, galaxies with extended star-forming disks but quenched inner regions, by leveraging the differences in star formation rates between the MPA-JHU and GSWLC catalogs. However, they also exhibit residual central emission within the region covered by the SDSS 3" fibre. The emission line analysis showed that the central emission in these galaxies originated either from ongoing star formation or low ionization nuclear emission line regions (LINERs) activity, suggesting diverse central ionization mechanisms. Based on the location of different structural components (bar, bulge, and disk) in spatially resolved UV–optical color maps using SDSS (r-band) and GALEX (far-UV; FUV; and near-UV; NUV) imaging data, we found that disks are star forming and bluer (NUV-r 4 mag) and dominated by older stellar populations. Following this, we derived NUV-r radial color profiles (which are a good photometric age indicator) to constrain the ages of the dominant stellar populations in different regions of these galaxies. The profiles clearly transition from red to blue at the bar end, with a corresponding median stellar age of ∼ 1 Gyr. We compared the NUV–r profiles of our sample with those of fully centrally quenched barred galaxies from our previous study, which showed no emission within the 3" SDSS fibre. Although NUV-r remains > 4 mag inside the bar region, indicating stellar populations older than ∼ 1 Gyr, our galaxies are systematically bluer and younger at the same radii than those of the fully quenched sample. This suggests that our current sample might represent an intermediate evolutionary stage in bar-driven quenching. To determine the role of low-luminosity AGN activity in star formation quenching, we estimated the black hole masses for our sample. All galaxies lie below the threshold (logM_ BH < 8. 0) associated with kinetic-mode AGN feedback, implying that AGN-driven outflows are unlikely to be the primary quenching mechanism. We also note that these galaxies except for one galaxy host pseudo-bulges. These findings suggest that the most likely mechanism driving the observed quenching in our sample galaxies is the action of bars and that these sample galaxies represent an evolutionary phase in the bar-driven quenching process, just before the inner region is completely quenched. Observations with a higher spatial resolution of the bar and central subkiloparsec region can help us to better constrain the bar-driven evolutionary pathways that lead to the quenching of star formation in barred spiral galaxies.
Renu et al. (Mon,) studied this question.
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