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The KMOS Deep Survey (KDS) – I. Dynamical measurements of typical star-forming galaxies at z ≃ 3.5

Turner, O.J.; Cirasuolo, M.; Harrison, C.M.; McLure, R.J.; Dunlop, J.S.; Swinbank, A.M.; Johnson, H.L.; Sobral, D.; Matthee, J.; Sharples, R.M.

The KMOS Deep Survey (KDS) – I. Dynamical measurements of typical star-forming galaxies at z ≃ 3.5 Thumbnail


O.J. Turner

M. Cirasuolo

C.M. Harrison

R.J. McLure

J.S. Dunlop

A.M. Swinbank

H.L. Johnson

D. Sobral

J. Matthee


We present dynamical measurements from the KMOS (K-band Multi-Object Spectrograph) Deep Survey (KDS), which is comprised of 77 typical star-forming galaxies at z z ≃ 3.5 in the mass range 9.0 < log(M⋆/M⊙) < 10.5. These measurements constrain the internal dynamics, the intrinsic velocity dispersions (σint) and rotation velocities (VC) of galaxies in the high-redshift Universe. The mean velocity dispersion of the galaxies in our sample is σint=70.8+3.3−3.1kms−1 σint=70.8−3.1+3.3kms−1 , revealing that the increasing average σint with increasing redshift, reported for z ≲ 2, continues out to z ≃ 3.5. Only 36 ± 8% of our galaxies are rotation-dominated (VC/σint > 1), with the sample average VC/σint value much smaller than at lower redshift. After carefully selecting comparable star-forming samples at multiple epochs, we find that the rotation-dominated fraction evolves with redshift with a z−0.2 dependence. The rotation-dominated KDS galaxies show no clear offset from the local rotation velocity-stellar mass (i.e. VC − M⋆) relation, although a smaller fraction of the galaxies are on the relation due to the increase in the dispersion-dominated fraction. These observations are consistent with a simple equilibrium model picture, in which random motions are boosted in high-redshift galaxies by a combination of the increasing gas fractions, accretion efficiency, specific star-formation rate and stellar feedback and which may provide significant pressure support against gravity on the galactic disk scale.


Turner, O., Cirasuolo, M., Harrison, C., McLure, R., Dunlop, J., Swinbank, A., …Sharples, R. (2017). The KMOS Deep Survey (KDS) – I. Dynamical measurements of typical star-forming galaxies at z ≃ 3.5. Monthly Notices of the Royal Astronomical Society, 471(2), 1280-1320.

Journal Article Type Article
Acceptance Date May 31, 2017
Online Publication Date Jun 3, 2017
Publication Date Oct 21, 2017
Deposit Date Jun 6, 2017
Publicly Available Date Jun 7, 2017
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 471
Issue 2
Pages 1280-1320
Related Public URLs


Accepted Journal Article (7.1 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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