Investigating the role of bars in quenching star formation using spatially resolved UV-optical colour maps

Abstract: Bars are ubiquitously found in disc galaxies and are known to drive galaxy evolution through secular processes. However, the specific contribution of bars in suppression of star formation (SF) is still under inspection which we investigate in this paper using spatially resolved UV-optical colour maps & radial color profiles of a sample of 17 centrally quenched (CQ) barred galaxies in redshift range 0.02-0.06. The sample is selected based on their location in M$_{\ast}$ - SFR plane. They are classified as passive based on parameters from MPA-JHU VAC, but non-passive based on the GSWLC catalog, indicating a passive inner region & recent star formation in their extended disc. We use archival SDSS r-band and GALEX FUV & NUV imaging data and created spatially resolved (FUV-NUV vs NUV-r) colour maps to understand the nature of UV emission from different regions of these galaxies. We then analyse their NUV-r radial profiles using NUV-r colour as a proxy for stellar population (SP) age. A control sample of 8 CQ unbarred galaxies is also analysed to disentangle the effect of bulge and bar in quenching SF. The CQ barred galaxies display redder colors (NUV-r $>$ 4-4.5 mag) in inner regions, up to the length of the bar, indicating the age of stellar population in these regions to be older than $>$ 1 Gyr. Most barred galaxies in our sample host pseudo bulges and do not host AGN, emphasizing most probable reason for the internal quenching is action of stellar bar. In comparison to the unbarred, the barred galaxies show redder colors to a larger spatial extent. We conclude that bars in their later stages of evolution turn the inner regions of galaxies redder, leading to quenching, with the effect being most prominent up to the ends of the bar and creating a region dominated by older SP. This may occur when bars have already funneled gas to the galactic centre leaving behind no fuel for further SF.