Journal Article

ΛCDM predictions for galaxy protoclusters – I. The relation between galaxies, protoclusters and quasars at <i>z</i>∼ 6

Roderik A. Overzier, Qi Guo, Guinevere Kauffmann, Gabriella De Lucia, Rychard Bouwens and Gerard Lemson

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 2, pages 577-594
Published in print April 2009 | ISSN: 0035-8711
Published online March 2009 | e-ISSN: 1365-2966 | DOI:
ΛCDM predictions for galaxy protoclusters – I. The relation between galaxies, protoclusters and quasars at z∼ 6

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Motivated by recent observational studies of the environment of z∼ 6 QSOs, we have used the Millennium Run (MR) simulations to construct a very large (∼4°× 4°) mock redshift survey of star-forming galaxies at z∼ 6. We use this simulated survey to study the relation between density enhancements in the distribution of i775-dropouts and Lyα emitters, and their relation to the most massive haloes and protocluster regions at z∼ 6. Our simulation predicts significant variations in surface density across the sky with some voids and filaments extending over scales of 1°, much larger than probed by current surveys. Approximately one-third of all z∼ 6 haloes hosting i-dropouts brighter than z= 26.5 mag (≈M*UV,z=6) become part of z= 0 galaxy clusters. i-dropouts associated with protocluster regions are found in regions where the surface density is enhanced on scales ranging from a few to several tens of arcminutes on the sky. We analyse two structures of i-dropouts and Lyα emitters observed with the Subaru Telescope and show that these structures must be the seeds of massive clusters in formation. In striking contrast, six z∼ 6 QSO fields observed with Hubble Space Telescope show no significant enhancements in their i775-dropout number counts. With the present data, we cannot rule out the QSOs being hosted by the most massive haloes. However, neither can we confirm this widely used assumption. We conclude by giving detailed recommendations for the interpretation and planning of observations by current and future ground- and space-based instruments that will shed new light on questions related to the large-scale structure at z∼ 6.

Keywords: galaxies: clusters: general; galaxies: high-redshift; galaxies: starburst; cosmology: observations; cosmology: theory; large-scale structure of Universe

Journal Article.  13780 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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