Redshift Evolution of Green Valley Galaxies in Different Environments from the Hyper Suprime-Cam Survey

Green valley galaxies represent the population that is likely to transition from star-forming to quiescent phases. To investigate the role of the environment in quenching star formation, we use the wide-field data from the Hyper Suprime-Cam Strategic Subaru Proposal survey to quantify the frequency...

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Bibliographic Details
Published in:	The Astrophysical journal 2020-05, Vol.894 (2), p.125
Main Authors:	Jian, Hung-Yu, Lin, Lihwai, Koyama, Yusei, Tanaka, Ichi, Umetsu, Keiichi, Hsieh, Bau-Ching, Higuchi, Yuichi, Oguri, Masamune, More, Surhud, Komiyama, Yutaka, Kodama, Tadayuki, Nishizawa, Atsushi J., Chang, Yu-Yen
Format:	Article
Language:	eng
Subjects:	Astronomy data analysis Astrophysics Environmental effects Evolution Galactic clusters Galactic evolution Galaxies Galaxy clusters Galaxy groups Green valley galaxies Large-scale structure of the universe Polls & surveys Quenching Red shift Star & galaxy formation Star formation Star formation rate Stars & galaxies Stellar evolution Valleys
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Summary:	Green valley galaxies represent the population that is likely to transition from star-forming to quiescent phases. To investigate the role of the environment in quenching star formation, we use the wide-field data from the Hyper Suprime-Cam Strategic Subaru Proposal survey to quantify the frequency of green valley galaxies in different environments and their redshift evolution. We find that the green valley fraction, in general, is less than 20% in any redshift and environment. The green valley fraction, when normalized to the total population, is higher in the field than that in groups or clusters and decreases with decreasing redshift and increasing mass. The lower fraction of transitional galaxies in denser environments could be a consequence of the lack of star-forming galaxies, which could be the progenitors of green valley galaxies. To assess the effect of the environment on star formation quenching, we define the effective green valley fraction as the ratio of the number of green valley galaxies to that of nonquiescent galaxies only. The effective green valley fraction for field galaxies is lower than that for group or cluster galaxies, which reveals a strong positive mass dependence and mild redshift evolution. Moreover, the specific star formation rate is reduced by 0.1-0.3 dex in groups or clusters. Our results thus imply that an ongoing slow quenching process has been acting in the dense environment since z ∼ 1.
ISSN:	0004-637X 1538-4357