Surface brightness of S^4^G face-on galaxies

In particular, we have studied the structural properties of those disks with a broken or down-bending profile. We find that, on average, disks with a genuine single-exponential profile have a scale length and a central surface brightness which are intermediate to those of the inner and outer components of a down-bending disk with the same total stellar mass.

In the particular case of barred galaxies, the ratio between the break and the bar radii (R_br_/R_bar_) depends strongly on the total stellar mass of the galaxy. For galaxies more massive than 10^10^M_{sun}_, the distribution is bimodal, peaking at R_br_/R_bar_~2 and ~3.5. The first peak, which is the most populated one, is linked to the outer Lindblad resonance of the bar, whereas the second one is consistent with a dynamical coupling between the bar and the spiral pattern.