CANDELS: CORRELATIONS OF SPECTRAL ENERGY DISTRIBUTIONS AND MORPHOLOGIES WITH STAR FORMATION STATUS FOR MASSIVE GALAXIES AT z {approx} 2
- School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
- Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching (Germany)
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
- Astronomy Department, University of Massachusetts, 710 N. Pleasant Street, Amherst, MA 01003 (United States)
- Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
We present a study on spectral energy distributions, morphologies, and star formation for an IRAC-selected extremely red object sample in the GOODS Chandra Deep Field-South. This work was enabled by new HST/WFC3 near-IR imaging from the CANDELS survey as well as the deepest available X-ray data from Chandra 4 Ms observations. This sample consists of 133 objects with the 3.6 {mu}m limiting magnitude of [3.6] = 21.5 and is approximately complete for galaxies with M{sub *} > 10{sup 11} M{sub Sun} at 1.5 {<=} z {<=} 2.5. We classify this sample into two types, quiescent and star-forming galaxies (SFGs), in the observed infrared color-color ([3.6]-[24] versus K - [3.6]) diagram. The further morphological study of this sample shows a consistent result with the observed color classification. The classified quiescent galaxies are bulge dominated and SFGs in the sample have disk or irregular morphologies. Our observed infrared color classification is also consistent with the rest-frame color (U - V versus V - J) classification. We also found that quiescent and SFGs are well separated in the nonparametric morphology parameter (Gini versus M{sub 20}) diagram measuring their concentration and clumpiness: quiescent galaxies have a Gini coefficient higher than 0.58 and SFGs have a Gini coefficient lower than 0.58. We argue that the star formation quenching process must lead to or be accompanied by the increasing galaxy concentration. One prominent morphological feature of this sample is that disks are commonly seen in this massive galaxy sample at 1.5 {<=} z {<=} 2.5: 30% of quiescent galaxies and 70% of SFGs with M{sub *} > 10{sup 11} M{sub Sun} have disks in their rest-frame optical morphologies. The prevalence of these extended, relatively undisturbed disks challenges the merging scenario as the main mode of massive galaxy formation.
- OSTI ID:
- 22036998
- Journal Information:
- Astrophysical Journal, Vol. 752, 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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