Galaxy Zoo: Secular evolution of barred galaxies from structural
  decomposition of multi-band images
  We present the results of two-component (disc+bar) and three-component
(disc+bar+bulge) multiwavelength 2D photometric decompositions of barred
galaxies in five SDSS bands ($ugriz$). This sample of $\sim$3,500 nearby
($z<0.06$) galaxies with strong bars selected from the Galaxy Zoo citizen
science project is the largest sample of barred galaxies to be studied using
photometric decompositions which include a bar component. With detailed
structural analysis we obtain physical quantities such as the bar- and
bulge-to-total luminosity ratios, effective radii, S\'ersic indices and colours
of the individual components. We observe a clear difference in the colours of
the components, the discs being bluer than the bars and bulges. An overwhelming
fraction of bulge components have S\'ersic indices consistent with being
pseudobulges. By comparing the barred galaxies with a mass-matched and
volume-limited sample of unbarred galaxies, we examine the connection between
the presence of a large-scale galactic bar and the properties of discs and
bulges. We find that the discs of unbarred galaxies are significantly bluer
compared to the discs of barred galaxies, while there is no significant
difference in the colours of the bulges. We find possible evidence of secular
evolution via bars that leads to the build-up of pseudobulges and to the
quenching of star formation in the discs. We identify a subsample of unbarred
galaxies with an inner lens/oval and find that their properties are similar to
barred galaxies, consistent with an evolutionary scenario in which bars
dissolve into lenses. This scenario deserves further investigation through both
theoretical and observational work.
