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

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.

Publication metadata

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

Year: 2017

Volume: 471

Issue: 2

Pages: 1280-1320

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


DOI: 10.1093/mnras/stx1366


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