Evolution of the fraction of clumpy galaxies at 0.2 < z < 1.0 in the cosmos field
- Department of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
- Graduate School of Science and Engineering, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)
- Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)
- Spitzer Science Center, 314-6 Caltech, Pasadena, CA 91125 (United States)
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, F-13388 Marseille (France)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- Max Planck Institut für Plasma Physik and Excellence Cluster, D-85748 Garching (Germany)
Using the Hubble Space Telescope/Advanced Camera for Surveys data in the COSMOS field, we systematically searched clumpy galaxies at 0.2 < z < 1.0 and investigated the fraction of clumpy galaxies and its evolution as a function of stellar mass, star formation rate (SFR), and specific SFR (SSFR). The fraction of clumpy galaxies in star-forming galaxies with M {sub star} > 10{sup 9.5} M {sub ☉} decreases with time from ∼0.35 at 0.8 < z < 1.0 to ∼0.05 at 0.2 < z < 0.4, irrespective of the stellar mass, although the fraction tends to be slightly lower for massive galaxies with M {sub star} > 10{sup 10.5} M {sub ☉} at each redshift. On the other hand, the fraction of clumpy galaxies increases with increasing both SFR and SSFR in all the redshift ranges we investigated. In particular, we found that the SSFR dependences of the fractions are similar among galaxies with different stellar masses, and the fraction at a given SSFR does not depend on the stellar mass in each redshift bin. The evolution of the fraction of clumpy galaxies from z ∼ 0.9 to z ∼ 0.3 seems to be explained by such SSFR dependence of the fraction and the evolution of SSFRs of star-forming galaxies. The fraction at a given SSFR also appears to decrease with time, but this can be due to the effect of the morphological k correction. We suggest that these results are understood by the gravitational fragmentation model for the formation of giant clumps in disk galaxies, where the gas mass fraction is a crucial parameter.
- OSTI ID:
- 22357034
- Journal Information:
- Astrophysical Journal, Vol. 786, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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