Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/217268

Title

First results from Z-FOURGE: discovery of a candidate cluster at z = 2.2 in COSMOS

Author(s)

Spitler, Lee R.;  Labbe, Ivo;  Glazebrook, Karl;  Persson, S. Eric;  Monson, Andy;  Papovich, Casey;  Tran, Kim-Vy H.;  Poole, Gregory B.;  Quadri, Ryan;  van Dokkum, Pieter;  Kelson, Daniel D.;  Kacprzak, Glenn G.;  McCarthy, Patrick J.;  Murphy, David;  Straatman, Caroline M. S.;  Tilvi, Vithal

Abstract

We report the first results from the Z-FOURGE survey: the discovery of a candidate galaxy cluster at z = 2.2 consisting of two compact overdensities with red galaxies detected at >20{\sigma} above the mean surface density. The discovery was made possible by a new deep (Ks < 24.8 AB 5{\sigma}) Magellan/FourStar near-IR imaging survey with 5 custom medium-bandwidth filters. The filters pinpoint the location of the Balmer/4000\AA\ break in evolved stellar populations at 1.5 < z < 3.5, yielding significantly more accurate photometric redshifts than possible with broadband imaging alone. The overdensities are within 1' of each other in the COSMOS field and appear to be embedded in a larger structure that contains at least one additional overdensity (\sim10{\sigma}). Considering the global properties of the overdensities, the z = 2.2 system appears to be the most distant example of a galaxy cluster with a population of red galaxies. A comparison to a large {\Lambda}CDM simulation suggests that the system may consist of merging subclusters, with properties in between those of z > 2 protoclusters with more diffuse distributions of blue galaxies and the lower-redshift galaxy clusters with prominent red sequences. The structure is completely absent in public optical catalogs in COSMOS and only weakly visible in a shallower near-IR survey. The discovery showcases the potential of deep near-IR surveys with medium-band filters to advance the understanding of environment and galaxy evolution at z > 1.5.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Astrophysical Journal Letters, Vol. 748, no. 2 (Apr 2012), article no. L21

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

COSMOS;  Galaxy clusters;  High redshift;  Large-scale structure of universe;  Z-FOURGE

Publisher

Institute of Physics Publishing

ISSN

2041-8205

Publisher URL

http://dx.doi.org/10.1088/2041-8205/748/2/L21

Copyright

Copyright © 2012. The American Astronomical Society. All rights reserved. The American Astronomical Society does not allow institutions to archive either the accepted manuscript or the published version of the article. However, you can find an earlier version of the full text here: http://arxiv.org/abs/1112.2691.

Research Projects

Mass assembly and galaxy evolution: measuring origins in deep time, Australian Research Council grant number DP1094370
The last 8 billion years of cosmic evolution, Australian Research Council grant number DP0772084
The fundamental physics governing the formation of cosmic structure, Australian Research Council grant number DP1093738

Peer reviewed