From Blue Star-forming to Red Passive: Galaxies in Transition in Different Environments

Journal
Date Issued
2015
Author(s)
•
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Fritz, Jacopo
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Paccagnella, Angela
DOI
Description
We thank the anonymous referee whose comments helped to improve the readability of the paper. This work was supported by the World Premier International Research Center Initiative (WPI), MEXT, Japan. It was also supported by the Kakenhi Grant-in-Aid for Young Scientists (B)(26870140) from the Japan Society for the Promotion of Science (JSPS). We thank Joe Liske, Simon Driver, and the whole MGC team for making their valuable data set public and easily accessible.
Abstract
Exploiting a mass-complete (M * > 1010.25 M ☉) sample at 0.03 rf color and morphologies to characterize galaxies, in particular those that show signs of an ongoing or recent transformation of their star-formation activity and/or morphology: green galaxies, red passive late types, and blue star-forming early types. Color fractions depend on mass and only for M * < 1010.7 M ☉ on environment. The incidence of red galaxies increases with increasing mass, and, for M * < 1010.7 M ☉, decreases toward the group outskirts and in binary and single galaxies. The relative abundance of green and blue galaxies is independent of environment and increases monotonically with galaxy mass. We also inspect galaxy structural parameters, star-formation properties, histories, and ages and propose an evolutionary scenario for the different subpopulations. Color transformations are due to a reduction and suppression of the star-formation rate in both bulges and disks that does not noticeably affect galaxy structure. Morphological transitions are linked to an enhanced bulge-to-disk ratio that is due to the removal of the disk, not to an increase of the bulge. Our modeling suggests that green colors might be due to star-formation histories declining with long timescales, as an alternative scenario to the classical "quenching" processes. Our results suggest that galaxy transformations in star-formation activity and morphology depend neither on the environment nor on being a satellite or the most massive galaxy of a halo. The only environmental dependence we find is the higher fast quenching efficiency in groups giving origin to poststarburst signatures.
Volume
798
Issue
1
Start page
52
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...798...52V
Rights
open.access
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