Tuesday

We present the results of a three-components (disc+bulge+bar) multiwavelength photometric decomposition in five SDSS bands on the largest sample of barred galaxies to date, using the novel GALFITM software. Using morphologies from the Galaxy Zoo citizen science project, we have created a catalogue of ~3,500 nearby barred galaxies which have been visually inspected for the presence of a bar. We obtain physical quantities such as the bar and bulge-to-total luminosity ratios, colours and Sérsic indices. We observe a clear difference in colour between the components, the discs being bluer than the bars and bulges. By comparing the barred galaxies with a mass-matched sample of unbarred galaxies, we find possible evidence suggesting that galactic bars quench the star formation in the discs and lead to the formation of pseudobulges in local barred galaxies.

We also used our fitting procedure to identify a subsample of galaxies with bars offset from their disc centres. We find that the majority of these galaxies are of Magellanic type, having low masses and characterised by the absence of a prominent bulge. Our findings are in good agreement with predictions from simulations of dwarf-dwarf tidal interactions producing off-centre bars (Pardy et al., 2016). However, conducting a nearest neighbour search we do not find a correlation between the offsets and companions. We discuss alternative scenarios that can give rise to the observed offsets such as interactions with dark companions and the effect of lopsided halo potentials.