BREAKS IN THIN AND THICK DISKS OF EDGE-ON GALAXIES IMAGED IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)
- Astronomy Division, Department of Physics, University of Oulu, P.O. Box 3000, FI-90014 (Finland)
- IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)
- Laboratoire d'Astrophysique de Marseille-LAM, Universite d'Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France)
- Instituto de Astrofisica de Canarias, E-38200 La Laguna (Spain)
- European Southern Observatory, Casilla 19001, Santiago 19 (Chile)
- National Radio Astronomy Observatory, Charlottesville, VA (United States)
- Department of Astronomy, University of Arizona, Tucson, AZ (United States)
- Space Telescope Science Institute, Baltimore, MD (United States)
- Departamento de Astrofisica, Universidad Complutense de Madrid, Madrid (Spain)
- Observatorio do Valongo, Universidade Federal de Rio de Janeiro, Ladeira Pedro Antonio, 43, Saude CEP 20080-090, Rio de Janeiro-RJ-Brazil (Brazil)
- The Observatories of the Carnegie Institution for Science, Pasadena, CA (United States)
- Department of Physics and Space Sciences, Florida Institute of Technology, 150 W. University Boulevard, Melbourne, FL 32901 (United States)
- European Space Agency, ESTEC, Keplerlaan 1, 2200-AG, Noordwijk (Netherlands)
Breaks in the radial luminosity profiles of galaxies have until now been mostly studied averaged over disks. Here, we study separately breaks in thin and thick disks in 70 edge-on galaxies using imaging from the Spitzer Survey of Stellar Structure in Galaxies. We built luminosity profiles of the thin and thick disks parallel to midplanes and we found that thin disks often truncate (77%). Thick disks truncate less often (31%), but when they do, their break radius is comparable with that in the thin disk. This suggests either two different truncation mechanisms-one of dynamical origin affecting both disks simultaneously and another one only affecting the thin disk-or a single mechanism that creates a truncation in one disk or in both depending on some galaxy property. Thin disks apparently antitruncate in around 40% of galaxies. However, in many cases, these antitruncations are an artifact caused by the superposition of a thin disk and a thick disk, with the latter having a longer scale length. We estimate the real thin disk antitruncation fraction to be less than 15%. We found that the ratio of the thick and thin stellar disk mass is roughly constant (0.2 < M{sub T} /M{sub t} < 0.7) for circular velocities v{sub c} > 120 km s{sup -1}, but becomes much larger at smaller velocities. We hypothesize that this is due to a combination of a high efficiency of supernova feedback and a slower dynamical evolution in lower-mass galaxies causing stellar thin disks to be younger and less massive than in higher-mass galaxies.
- OSTI ID:
- 22086411
- Journal Information:
- Astrophysical Journal, Vol. 759, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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