Morphologies of ~190,000 Galaxies at z = 0-10 Revealed with HST Legacy Data. II. Evolution of Clumpy Galaxies
Abstract
We investigate the evolution of clumpy galaxies with Hubble Space Telescope (HST) samples of ∼17,000 photo-z and Lyman break galaxies at z ≃ 0-8. We detect clumpy galaxies with off-center clumps in a self-consistent algorithm that is well tested with previous study results, and we measure the number fraction of clumpy galaxies at the rest-frame UV, {f}{{clumpy}}{{UV}}. We identify an evolutionary trend of {f}{{clumpy}}{{UV}} over z ≃ 0-8 for the first time: {f}{{clumpy}}{{UV}} increases from z ≃ 8 to z ≃ 1-3 and subsequently decreases from z ≃ 1 to z ≃ 0, which follows the trend of the Madau-Lilly plot. A low average Sérsic index of n ≃ 1 is found in the underlining components of our clumpy galaxies at z ≃ 0-2, indicating that typical clumpy galaxies have disk-like surface brightness profiles. Our {f}{{clumpy}}{{UV}} values correlate with physical quantities related to star formation activities for star-forming galaxies at z ≃ 0-7. We find that clump colors tend to be red at a small galactocentric distance for massive galaxies with {log}{M}*/{M}⊙ ≳ 11. All of these results are consistent with the picture that a majority of clumps form in the violent disk instability and migrate into the galactic centers.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2016
- DOI:
- 10.3847/0004-637X/821/2/72
- arXiv:
- arXiv:1511.07054
- Bibcode:
- 2016ApJ...821...72S
- Keywords:
-
- cosmology: observations;
- early universe;
- galaxies: formation;
- galaxies: high-redshift;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 20 pages, 12 figures, accepted for publication in ApJ