Star Formation in Massive Galaxies at Redshift z ~ 0.5
Xu,Kun1; Liu,Chengze1; Jing,Yipeng1,2; Wang,Yunchong3,4; Lu,Shengdong5,6
Source PublicationThe Astrophysical Journal
AbstractAbstract It is believed that massive galaxies have quenched their star formation because of active galactic nucleus feedback. However, recent studies have shown that some massive galaxies are still forming stars. We analyze the morphology of star formation regions for galaxies of stellar masses larger than 1011.3 M⊙ at around redshift zr?=?0.5 using u???z color images. We find that about 20% of the massive galaxies are star-forming (SF) galaxies, and most of them (~85%) have asymmetric structures induced by recent mergers. Moreover, for these asymmetric galaxies, we find that the asymmetry of the SF regions becomes larger for bluer galaxies. Using the Illustris simulation, we can qualitatively reproduce the observed relation between asymmetry parameter and color. Furthermore, using the merger trees in the simulation, we find a correlation between the color of the main branch galaxies at zr?=?0.5 and the sum of the star formation rates of the recently accreted galaxies, which implies that star formation of the accreted galaxies has contributed to the observed star formation of the massive (host) galaxies (ex situ star formation). Furthermore, we find two blue and symmetric galaxies, candidates for massive blue disks, in our observed sample, which indicates that about ~10% of massive SF galaxies are forming stars in the normal mode of disk star formation (in situ star formation). With the simulation, we find that the disk galaxies at zr?≈?0.5 should have experienced few major mergers during the last 4.3 Gyr.
KeywordGalaxy mergers Galaxy infall Galaxy disks Star formation Galaxy quenching
WOS IDIOP:0004-637X-895-2-ab8fa0
PublisherThe American Astronomical Society
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Document Type期刊论文
Affiliation1.Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, People’s Republic of China;,
2.Tsung-Dao Lee Institute, and Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai Jiao Tong University, Shanghai, 200240, People’s Republic of China
3.Department of Astronomy and Center for Astrophysics, Tsinghua University, Beijing, 100084, People’s Republic of China
4.Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics, Stanford University, Stanford, 94305, USA
5.National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of China
6.University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
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GB/T 7714
Xu,Kun,Liu,Chengze,Jing,Yipeng,等. Star Formation in Massive Galaxies at Redshift z ~ 0.5[J]. The Astrophysical Journal,2020,895(2).
APA Xu,Kun,Liu,Chengze,Jing,Yipeng,Wang,Yunchong,&Lu,Shengdong.(2020).Star Formation in Massive Galaxies at Redshift z ~ 0.5.The Astrophysical Journal,895(2).
MLA Xu,Kun,et al."Star Formation in Massive Galaxies at Redshift z ~ 0.5".The Astrophysical Journal 895.2(2020).
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