Evidence of Bar-induced Secular Evolution in the Inner Regions of
  Stellar Discs in Galaxies: What Shapes Disc Galaxies?
  We present evidence of bar-induced secular evolution in galactic discs using
3.6 ${\mu m}$ images of nearby galaxies from the Spitzer Survey of Stellar
Structure in Galaxies (S4G). We find that among massive galaxies
($M_{star}/M_{sun}> 10^{10}$), longer bars tend to reside in inner discs having
a flatter radial profile. Such galaxies show a light deficit in the disc
surrounding the bar, within the bar radius and often show a $\Theta$-shaped
morphology. We quantify this deficit and find that among all galaxies explored
in this study (with $10^{9}<M_{star}/M_{sun}< 10^{11}$), galaxies with a
stronger bar (i.e. longer and/or with a higher Bar/T) show a more pronounced
deficit. We also examine simulation snapshots to confirm and extend results by
Athanassoula and Misiriotis, showing that as bars evolve they become longer,
while the light deficit in the disc becomes more pronounced. Theoretical
studies have predicted that, as a barred galaxy evolves, the bar captures disc
stars in its immediate neighbourhood so as to make the bar longer, stronger and
thinner. Hence, we claim that the light deficit in the inner disc is produced
by bars, which thus take part in shaping the mass distribution of their host
galaxies.
