THE SIZE-STAR FORMATION RELATION OF MASSIVE GALAXIES AT 1.5 < z < 2.5
- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Mariesvej 30, DK-2100 Copenhagen (Denmark)
- Leiden Observatory, Postbus 9513, 2300 RA Leiden (Netherlands)
- Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States)
- Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85748 Garching (Germany)
- Carnegie Observatories, 813 Santa Barbara street, Pasadena, CA-91101 (United States)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden street, Cambridge, MA 02138 (United States)
- Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
We study the relation between size and star formation activity in a complete sample of 225 massive (M{sub *} > 5 x 10{sup 10} M {sub sun}) galaxies at 1.5 < z < 2.5, selected from the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis model fits to the observed rest-frame UV-NIR spectral energy distributions, and independent MIPS 24 mum observations, 65% of the galaxies are actively forming stars, while 35% are quiescent. Using sizes derived from two-dimensional surface brightness profile fits to high-resolution (FWHM{sub PSF} approx 0.''45) ground-based ISAAC data, we confirm and improve the significance of the relation between star formation activity and compactness found in previous studies, using a large, complete mass-limited sample. At z approx 2, massive quiescent galaxies are significantly smaller than massive star-forming galaxies, and a median factor of 0.34 +- 0.02 smaller than galaxies of similar mass in the local universe. Thirteen percent of the quiescent galaxies are unresolved in the ISAAC data, corresponding to sizes <1 kpc, more than five times smaller than galaxies of similar mass locally. The quiescent galaxies span a Kormendy relation which, compared to the relation for local early types, is shifted to smaller sizes and brighter surface brightnesses and is incompatible with passive evolution. The progenitors of the quiescent galaxies were likely dominated by highly concentrated, intense nuclear starbursts at z approx 3-4, in contrast to star-forming galaxies at z approx 2 which are extended and dominated by distributed star formation.
- OSTI ID:
- 21378396
- Journal Information:
- Astrophysical Journal, Vol. 705, Issue 1; Other Information: DOI: 10.1088/0004-637X/705/1/255; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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