The discovery of primeval large-scale structures with forming clusters at redshift

Masami Ouchi, Kazuhiro Shimasaku, Masayuki Akiyama, Kazuhiro Sekiguchi, Hisanori Furusawa, Sadanori Okamura, Nobunari Kashikawa, Masanori Iye, Tadayuki Kodama, Tomoki Saito, Toshiyuki Sasaki, Chris Simpson, Tadafumi Takata, Toru Yamada, Hitomi Yamanoi, Makiko Yoshida, Michitoshi Yoshida

Research output: Contribution to journalArticlepeer-review

161 Citations (Scopus)


We report the discovery of primeval large-scale structures (LSSs) including two protoclusters in a forming phase at z = 5.7. We carried out extensive deep narrowband imaging in the 1 deg2 sky of the Subaru/XMM-Newton Deep Field and obtained a cosmic map of 515 Lyα emitters (LAEs) in a volume with a transverse dimension of 180 Mpc × 180 Mpc and a depth of ∼40 Mpc in comoving units. This cosmic map shows filamentary LSSs, including clusters and surrounding 10-40 Mpc scale voids, similar to the present-day LSSs. Our spectroscopic follow-up observations identify overdense regions in which two dense clumps of LAEs with a sphere of 1 Mpc diameter in physical units are included. These clumps show about 130 times higher star formation rate density, mainly due to a large overdensity, ∼80, of LAEs. These clumps would be clusters in a formation phase involving a burst of galaxy formation.

Original languageEnglish
Pages (from-to)L1-L4
JournalAstrophysical Journal
Issue number1 II
Publication statusPublished - 2005 Feb 10


  • Galaxies: clusters: general
  • Galaxies: formation
  • Large-scale structure of universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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