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Discovery of a Supercluster at z ~ 0.91 and Testing the ΛCDM Cosmological Model

Kim, Jae-Woo; Im, Myungshin; Lee, Seong-Kook; Edge, Alastair C.; Hyun, Minhee; Kim, Dohyeong; Choi, Changsu; Hong, Jueun; Jeon, Yiseu; Jun, Hyunsung David; Karouzos, Marios; Kim, Duho; Kim, Ji Hoon; Kim, Yongjung; Park, Won-Kee; Taak, Yoon Chan; Yoon, Yongmin

Discovery of a Supercluster at z ~ 0.91 and Testing the ΛCDM Cosmological Model Thumbnail


Jae-Woo Kim

Myungshin Im

Seong-Kook Lee

Minhee Hyun

Dohyeong Kim

Changsu Choi

Jueun Hong

Yiseu Jeon

Hyunsung David Jun

Marios Karouzos

Duho Kim

Ji Hoon Kim

Yongjung Kim

Won-Kee Park

Yoon Chan Taak

Yongmin Yoon


The ΛCDM cosmological model successfully reproduces many aspects of the galaxy and structure formation of the universe. However, the growth of large-scale structures (LSSs) in the early universe is not well tested yet with observational data. Here, we have utilized wide and deep optical–near-infrared data in order to search for distant galaxy clusters and superclusters (0.8 < z < 1.2). From the spectroscopic observation with the Inamori Magellan Areal Camera and Spectrograph (IMACS) on the Magellan telescope, three massive clusters at z ~ 0.91 are confirmed in the SSA22 field. Interestingly, all of them have similar redshifts within Δ z ~ 0.01 with velocity dispersions ranging from 470 to 1300 km s−1. Moreover, as the maximum separation is ~15 Mpc, they compose a supercluster at z ~ 0.91, meaning that this is one of the most massive superclusters at this redshift to date. The galaxy density map implies that the confirmed clusters are embedded in a larger structure stretching over ~100 Mpc. ΛCDM models predict about one supercluster like this in our surveyed volume, consistent with our finding so far. However, there are more supercluster candidates in this field, suggesting that additional studies are required to determine if the ΛCDM cosmological model can successfully reproduce the LSSs at high redshift.


Kim, J., Im, M., Lee, S., Edge, A. C., Hyun, M., Kim, D., …Yoon, Y. (2016). Discovery of a Supercluster at z ~ 0.91 and Testing the ΛCDM Cosmological Model. Astrophysical Journal Letters, 821(1),

Journal Article Type Article
Acceptance Date Mar 28, 2016
Online Publication Date Apr 11, 2016
Publication Date Apr 11, 2016
Deposit Date Sep 20, 2016
Publicly Available Date Dec 1, 2016
Journal Astrophysical Journal Letters
Print ISSN 2041-8205
Electronic ISSN 2041-8213
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 821
Issue 1
Related Public URLs


Published Journal Article (1.1 Mb)

Copyright Statement
© 2016. The American Astronomical Society

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