Understanding the evolution of disk galaxies through the bars

Bars provide us important clues to understand the evolution of disk galaxies. Because bars are formed out of disk material, their initial surface brightness profiles are thought to be similar to those of disks. As bars evolve, their profiles change from exponential (disk-like) to flat, and this would result in a modification of structural properties of disks. I will present results from two-dimensional 3.6 μm image decompositions of 144 face-on barred galaxies from the Spitzer Survey of Stellar Structure in Galaxies (S4G). I will show the relation between bar surface brightness profiles and the bulge-to-total ratio (B/T) and stellar mass of their host galaxies, and show how these results fit in the observed cosmological evolution of barred galaxies. I will discuss implications for estimating dynamical age of bars, i.e., the time elapsed since the bar formation, and present evidences of bar driven secular evolution onthe inner part of disk galaxies.