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The KMOS Cluster Survey (KCS). III. Fundamental plane of cluster galaxies at z ≃ 1.80 in JKCS 041

Abstract:
We present data for 16 galaxies in the overdensity JKCS 041 at z ≃ 1.80 as part of the K-band Multi-Object Spectrograph (KMOS) Cluster Survey (KCS). With 20 hr integrations, we have obtained deep absorption-line spectra from which we derived velocity dispersions for seven quiescent galaxies. We combined photometric parameters derived from Hubble Space Telescope images with the dispersions to construct a fundamental plane (FP) for quiescent galaxies in JKCS 041. From the zero-point evolution of the FP, we derived a formation redshift for the galaxies of z form = 3.0 ± 0.3, corresponding to a mean age of 1.4 ± 0.2 Gyr. We tested the effect of structural and velocity dispersion evolution on our FP zero-point and found a negligible contribution when using dynamical mass-normalized parameters (∼3%) but a significant contribution from stellar-mass-normalized parameters (∼42%). From the relative velocities of the galaxies, we probed the 3D structure of these 16 confirmed members of JKCS 041 and found that a group of galaxies in the southwest of the overdensity had systematically higher velocities. We derived ages for the galaxies in the different groups from the FP. We found that the eastextending group had typically older galaxies (2.1 +0.3 0.2 Gyr) than those in the southwest group (0.3 ± 0.2 Gyr). Although based on small numbers, the overdensity dynamics, morphology, and age results could indicate that JKCS 041 is in formation and may comprise two merging groups of galaxies. This result could link large-scale structure to ages of galaxies for the first time at this redshift.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.3847/1538-4357/aa96a6

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS Division
Department:
Physics; Astrophysics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS Division
Department:
Physics; Astrophysics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Role:
Author


Publisher:
Institute of Physics
Journal:
Astrophysical Journal More from this journal
Volume:
850
Issue:
2
Pages:
203
Publication date:
2017-12-01
Acceptance date:
2017-10-25
DOI:
EISSN:
1538-4357
ISSN:
0004-637X


Keywords:
Pubs id:
pubs:812274
UUID:
uuid:091b4286-614e-4fb5-b49a-1e363a518c96
Local pid:
pubs:812274
Source identifiers:
812274
Deposit date:
2018-01-23

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