FIRST RESULTS FROM Z -FOURGE : DISCOVERY OF A CANDIDATE CLUSTER AT z = 2.2 IN COSMOS
- Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia)
- Carnegie Observatories, Pasadena, CA 91101 (United States)
- George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX, 77843-4242 (United States)
- Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
- Sterrewacht Leiden, Leiden University, NL-2300 RA Leiden (Netherlands)
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 {approx}> 20{sigma} above the mean surface density. The discovery was made possible by a new deep (K{sub s} {approx}< 24.8 AB 5{sigma}) Magellan/FOURSTAR near-IR imaging survey with five custom medium-bandwidth filters. The filters pinpoint the location of the Balmer/4000 A 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 ({approx}10{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.
- OSTI ID:
- 22047943
- Journal Information:
- Astrophysical Journal Letters, Vol. 748, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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