The KMOS Cluster Survey (KCS). III. Fundamental Plane of Cluster Galaxies at z ≃ 1.80 in JKCS 041

Prichard, Laura J. and Davies, Roger L. and Beifiori, Alessandra and Chan, Jeffrey C.C. and Cappellari, Michele and Houghton, Ryan C.W. and Mendel, J. Trevor and Bender, Ralf and Galametz, Audrey and Saglia, Roberto P. and Stott, John P. and Wilman, David J. and Lewis, Ian J. and Sharples, Ray and Wegner, Michael (2017) The KMOS Cluster Survey (KCS). III. Fundamental Plane of Cluster Galaxies at z ≃ 1.80 in JKCS 041. The Astrophysical Journal, 850 (2). ISSN 0004-637X

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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 zform = 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.

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Journal Article
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The Astrophysical Journal
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This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.3847/1538-4357/aa96a6
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03 Jan 2018 16:52
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22 Nov 2022 05:19