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Lookup NU author(s): Dr Christopher HarrisonORCiD
This is the final published version of an article that has been published in its final definitive form by Oxford University Press, 2017.
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© 2017 The Authors. We present dynamical measurements from the KMOS (K-band multi-object spectrograph) Deep Survey (KDS), which comprises 77 typical star-forming galaxies at 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 -3.1 +3.3 km s-1, revealing that the increasing average σint with increasing redshift, reported for z≲2, continues out to z ≃ 3.5. Only 36 ± 8 per cent of our galaxies are rotation-dominated (VC/σ int > 1), with the sample average VC/σ int value much smaller than at lower redshift. After carefully selecting comparable star-forming samples at multiple epochs, we find that the rotationdominated 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 disc scale.
Author(s): Turner OJ, Cirasuolo M, Harrison CM, McLure RJ, Dunlop JS, Swinbank AM, Johnson HL, Sobral D, Matthee J, Sharples RM
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Print publication date: 01/10/2017
Online publication date: 03/06/2017
Acceptance date: 31/05/2017
Date deposited: 04/02/2020
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
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