AEGIS: THE MORPHOLOGIES OF GREEN GALAXIES AT 0.4 < z < 1.2

• Published in: The Astrophysical journal 2011-08, Vol.736 (2), p.110-jQuery1323905477223='48'
• Main Authors: MENDEZ, Alexander J, COIL, Alison L, LOTZ, Jennifer, SALIM, Samir, MOUSTAKAS, John, SIMARD, Luc
• Format: Article
• Language: English
• Subjects: Astronomy; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Earth, ocean, space; EVOLUTION; Exact sciences and technology; GALACTIC EVOLUTION; GALAXIES; MORPHOLOGY; QUENCHING; STARS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637x/736/2/110

We present quantitative morphologies of ~300 galaxies in the optically defined green valley at 0.4 < z < 1.2, in order to constrain the mechanism(s) responsible for quenching star formation in the bulk of this population. The sample is selected from galaxies in the All-Wavelength Extended Groth Strip International Survey (AEGIS). While the green valley is defined using optical U -- B colors, we find that using a green valley sample defined using NUV -- R colors does not change the results. Using Hubble Space Telescope/Advanced Camera for Surveys imaging, we study several quantitative morphological parameters including CAS, B/T from GIM2D, and Gini/M 20. We find that the green galaxy population is intermediate between the red and blue galaxy populations in terms of concentration, asymmetry, and morphological type and merger fraction estimated using Gini/M 20. We find that most green galaxies are not classified as mergers; in fact, the merger fraction in the green valley is lower than in the blue cloud. We show that at a given stellar mass, green galaxies have higher concentration values than blue galaxies and lower concentration values than red galaxies. Additionally, we find that 12% of green galaxies have B/T = 0 and 21% have B/T