J. C. Muñoz-Mateos, K. Sheth, A. Gil de Paz, S. E. Meidt, E. Athanassoula, A. Bosma, S. Comerón, D. M. Elmegreen, B. G. Elmegreen, S. Erroz-Ferrer, D. A. Gadotti, J. L. Hinz, L. C. Ho, B. Holwerda, T. H. Jarrett, T. Kim, J. H. Knapen, J. Laine, E. Laurikainen, B. F. Madore, K. Menendez-Delmestre, T. Mizusawa, M. Regan, H. Salo, E. Schinnerer, M. Seibert, R. Skibba, D. Zaritsky
We have analyzed the radial distribution of old stars in a sample of 218 nearby face-on disks, using deep 3.6um images from the Spitzer Survey of Stellar Structure in Galaxies (S4G). 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 case of barred galaxies, the ratio between the break and the bar radii (Rbr/Rbar) depends strongly on the total stellar mass of the galaxy. For galaxies more massive than 10^10 Msun, the distribution is bimodal, peaking at Rbr/Rbar~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. For galaxies below 10^10 Msun, breaks are found up to ~10 Rbar, but we show that they could still be caused by resonances given the rising nature of rotation curves in these low-mass disks. While not ruling out star formation thresholds, our results imply that radial stellar migration induced by non-axysymmetric features can be responsible not only for those breaks at 2 Rbar, but also for many of those found at larger radii.
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http://arxiv.org/abs/1304.6083
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