Detalles de publicación
PP 013035
THE IMPACT OF BARS ON DISK BREAKS AS PROBED BY S4G IMAGING
1 National Radio Astronomy Observatory / NAASC, 520 Edgemont Road, Charlottesville, VA 22903
2 DepartamentodeAstrof ́ısica,UniversidadComplutensede Madrid, Madrid 28040, Spain
3 Max-Planck-Institut fu ̈r Astronomie, K ̈onigstuhl 17, 69117 Heidelberg, Germany
4 Aix Marseille Universite, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388, Marseille, France
5 Department of Physical Sciences/Astronomy Division, Univer- sity of Oulu, FIN-90014, Finland
6 Vassar College, Dept. of Physics and Astronomy, Poughkeep- sie, NY 12604
7 IBM Research Division, T.J. Watson Research Center, York- town Hts., NY 10598
8 Instituto de Astrof ́ısica de Canarias, 38205 La Laguna, Spain
9 DepartamentodeAstrof ́ısica,UniversidaddeLaLaguna, 38206 La Laguna, Spain
10 European Southern Observatory, Casilla 19001, Santiago 19, Chile
11 University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721
12 The Observatories, Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101
13 European Space Agency, ESTEC, Keplerlaan 1, 2200 AG, Noordwijk, the Netherlands
14 Astrophysics, Cosmology and Gravity Centre, Department of Astronomy, University of Cape Town, Private Bag X3, Ronde- bosch 7701, South Africa
15 Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Korea
16 Finnish Centre for Astronomy with ESO (FINCA), University of Turku
17 Observatorio do Valongo, Universidade Federal de Rio de Janeiro, Ladeira Pedro Antonio, 43, Saude CEP 20080-090, Rio de Janeiro - RJ - Brasil
18 Florida Institute of Technology, Melbourne, FL 32901
19 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218
We have analyzed the radial distribution of old stars in a sample of 218 nearby face-on disks, using deep 3.6μm 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 particular 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 1010 M⊙, 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 1010 M⊙, breaks are found up to ∼ 10Rbar, 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 ∼ 2Rbar, but also for many of those found at larger radii.