Redshift Evolution of Green Valley Galaxies in Different Environments from the Hyper Suprime-Cam Survey
Redshift Evolution of Green Valley Galaxies in Different Environments from the Hyper Suprime-Cam Survey
复制标题
DOI：
10.3847/1538-4357/ab86a8
复制
发表时间：
2020-05
期刊：
影响因子：
--
通讯作者：
H. Jian;Lihwai Lin;Y. Koyama;I. Tanaka;K. Umetsu;B. Hsieh;Y. Higuchi;M. Oguri;S. More;Y. Komiyama;T. Kodama;A. Nishizawa;Yu-Yen Chang
中科院分区：
文献类型：
--
作者：
H. Jian;Lihwai Lin;Y. Koyama;I. Tanaka;K. Umetsu;B. Hsieh;Y. Higuchi;M. Oguri;S. More;Y. Komiyama;T. Kodama;A. Nishizawa;Yu-Yen Chang
绿谷星系代表了可能从恒星形成阶段过渡到静止阶段的星系群。为了研究环境在猝灭恒星形成中的作用，我们使用了来自Hyper SuPrime-Cam Strategic Subaru计划调查的广域数据来量化不同环境下绿谷星系的频率及其红移演化。我们发现，在任何红移和环境中，绿谷分数一般都小于20%。当归一化为总种群时，绿谷份额在野外高于群组或群组，并随着红移的减小和质量的增加而减小。在密度较高的环境中，过渡星系的比例较低，这可能是因为缺乏恒星形成星系，而恒星形成星系可能是绿谷星系的祖先。为了评估环境对恒星形成猝灭的影响，我们将有效绿谷分数定义为绿谷星系数与非静止星系数之比。场星系的有效绿谷分数低于星系团或星系团星系，表现出强烈的正质量依赖性和轻微的红移演化。此外，星团或星团的比恒星形成率降低了0.1-0.3dex。因此，我们的结果表明，从z∼1开始，稠密环境中一直存在一个正在进行的缓慢猝灭过程。
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.