THE MASS PROFILE AND SHAPE OF BARS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G): SEARCH FOR AN AGE INDICATOR FOR BARS

Journal Article · Tue Jan 20 00:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/799/1/99· OSTI ID:22364437

Kim, Taehyun; Lee, Myung Gyoon ^[1]; Sheth, Kartik; Muñoz-Mateos, Juan-Carlos ^[2]; Gadotti, Dimitri A. ^[3]; Zaritsky, Dennis ^[4]; Elmegreen, Bruce G. ^[5]; Athanassoula, E.; Bosma, Albert ^[6]; Holwerda, Benne ^[7]; Ho, Luis C. ^[8]; Comerón, Sébastien; Laurikainen, Eija; Salo, Heikki ^[9]; Knapen, Johan H.; Erroz-Ferrer, Santiago ^[10]; Hinz, Joannah L. ^[11]; Buta, Ronald J. ^[12]; Kim, Minjin ^[13]; Madore, Barry F. ^[14] ; others, and

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1. Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)
2. National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
3. European Southern Observatory, Casilla 19001, Santiago 19 (Chile)
4. University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States)
5. IBM Research Division, T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States)
6. Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388 Marseille (France)
7. European Space Agency, ESTEC, Keplerlaan 1, 2200-AG, Noordwijk (Netherlands)
8. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
9. Division of Astronomy, Department of Physical Sciences, University of Oulu, Oulu, FIN-90014 (Finland)
10. Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain)
11. MMTO, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States)
12. Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States)
13. Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
14. The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

We have measured the radial light profiles and global shapes of bars using two-dimensional 3.6 μm image decompositions for 144 face-on barred galaxies from the Spitzer Survey of Stellar Structure in Galaxies. The bar surface brightness profile is correlated with the stellar mass and bulge-to-total (B/T) ratio of their host galaxies. Bars in massive and bulge-dominated galaxies (B/T > 0.2) show a flat profile, while bars in less massive, disk-dominated galaxies (B/T ∼ 0) show an exponential, disk-like profile with a wider spread in the radial profile than in the bulge-dominated galaxies. The global two-dimensional shapes of bars, however, are rectangular/boxy, independent of the bulge or disk properties. We speculate that because bars are formed out of disks, bars initially have an exponential (disk-like) profile that evolves over time, trapping more disk stars to boxy bar orbits. This leads bars to become stronger and have flatter profiles. The narrow spread of bar radial profiles in more massive disks suggests that these bars formed earlier (z > 1), while the disk-like profiles and a larger spread in the radial profile in less massive systems imply a later and more gradual evolution, consistent with the cosmological evolution of bars inferred from observational studies. Therefore, we expect that the flatness of the bar profile can be used as a dynamical age indicator of the bar to measure the time elapsed since the bar formation. We argue that cosmic gas accretion is required to explain our results on bar profile and the presence of gas within the bar region.

• OSTI ID: 22364437
• Journal Information: Astrophysical Journal, Vol. 799, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BRIGHTNESS
COSMOLOGY
GALACTIC EVOLUTION
GALAXIES
IMAGES
MASS
STARS
SURFACES
TRAPPING
VISIBLE RADIATION