A massive protocluster of galaxies at a redshift of z≈5.3

Peter L. Capak, Dominik Riechers, Nick Z. Scoville, Chris Carilli, Pierre Cox, Roberto Neri, Brant Robertson, Mara Salvato, Eva Schinnerer, Lin Yan, Grant W. Wilson, Min Yun, Francesca Civano, Martin Elvis, Alexander Karim, Bahram Mobasher, Johannes G. Staguhn

Research output: Contribution to journalArticlepeer-review

238 Scopus citations


Massive clusters of galaxies have been found that date from as early as 3.9 billion years (3.9Gyr; z = 1.62) after the Big Bang, containing stars that formed at even earlier epochs. Cosmological simulations using the current cold dark matter model predict that these systems should descend from protoclusters-early overdensities of massive galaxies that merge hierarchically to form a cluster. These protocluster regions themselves are built up hierarchically and so are expected to contain extremely massive galaxies that can be observed as luminous quasars and starbursts. Observational evidence for this picture, however, is sparse because high-redshift protoclusters are rare and difficult to observe. Here we report a protocluster region that dates from 1Gyr (z = 5.3) after the Big Bang. This cluster of massive galaxies extends over more than 13 megaparsecs and contains a luminous quasar as well as a system rich in molecular gas. These massive galaxies place a lower limit of more than 4×1011 solar masses of dark and luminous matter in this region, consistent with that expected from cosmological simulations for the earliest galaxy clusters.

Original languageEnglish (US)
Pages (from-to)233-235
Number of pages3
Issue number7333
StatePublished - Feb 10 2011

ASJC Scopus subject areas

  • General


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