The stellar mass distribution of S$^{4}$G disk galaxies
  We use 3.6 $\mu$m imaging from the S$^{4}$G survey to characterize the
typical stellar density profiles ($\Sigma_{\ast}$) and bars as a function of
fundamental galaxy parameters (e.g. the total stellar mass $M_{\ast}$),
providing observational constraints for galaxy simulation models to be compared
with. We rescale galaxy images to a common frame determined by the size in
physical units, by their disk scalelength, or by their bar size and
orientation. We stack the resized images to obtain statistically representative
average stellar disks and bars. For a given $M_{\ast}$ bin ($\ge
10^{9}M_{\odot}$), we find a significant difference in the stellar density
profiles of barred and non-barred systems that gives evidence for bar-induced
secular evolution of disk galaxies: (i) disks in barred galaxies show larger
scalelengths and fainter extrapolated central surface brightnesses, (ii) the
mean surface brightness profiles of barred and non-barred galaxies intersect
each other slightly beyond the mean bar length, most likely at the bar
corotation, and (iii) the central mass concentration of barred galaxies is
larger (by almost a factor 2 when $T<5$) than in their non-barred counterparts.
We also show that early- and intermediate-type spirals ($0 \le T < 5$) host
intrinsically narrower bars than the later types and S0s, whose bars are
oval-shaped. We show a clear correlation between galaxy family and bar
ellipticity.
