AEGIS : the morphologies of green galaxies at 0.4 < z < 1.2

  1. Get@NRC: AEGIS : the morphologies of green galaxies at 0.4 < z < 1.2 (Opens in a new window)
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Journal titleThe Astrophysical Journal
Article number110
Subjectgalaxies: evolution; galaxies: high-redshift; galaxies: statistics; galaxies: structure
AbstractWe present quantitative morphologies similar to 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 <= 0.05. Our results show that green galaxies are generally massive (M * similar to 10(10.5) M sun disk galaxies with high concentrations. We conclude that major mergers are likely not the sole mechanism responsible for quenching star formation in this population and that either other external processes or internal secular processes play an important role both in driving gas toward the center of these galaxies and in quenching star formation.
Publication date
PublisherThe American Astronomical Society
AffiliationNational Research Council Canada; NRC Herzberg Institute of Astrophysics
Peer reviewedYes
NPARC number19793790
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Record identifier3c92af5b-ba61-470c-b800-ccb3d9396312
Record created2012-04-10
Record modified2016-07-18
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