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The KMOS Redshift One Spectroscopic Survey (KROSS): The origin of disc turbulence in z≈1 star-forming galaxies

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, 2018.

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© 2017 The Author(s).We analyse the velocity dispersion properties of 472 z~0.9 star-forming galaxies observed as part of the KMOS Redshift One Spectroscopic Survey (KROSS). The majority of this sample is rotationally dominated (83 ± 5 per cent with vC/σ0 > 1) but also dynamically hot and highly turbulent. After correcting for beam smearing effects, the median intrinsic velocity dispersion for the final sample is σ0 =43.2 ± 0.8 kms-1 with a rotational velocity to dispersion ratio of vC/σ0 =2.6 ± 0.1. To explore the relationship between velocity dispersion, stellar mass, star formation rate, and redshift, we combine KROSS with data from the SAMI survey (z~0.05) and an intermediate redshift MUSE sample (z~0.5). Whilst there is, at most, a weak trend between velocity dispersion and stellar mass, at fixed mass there is a strong increase with redshift. At all redshifts, galaxies appear to follow the same weak trend of increasing velocity dispersion with star formation rate. Our results are consistent with an evolution of galaxy dynamics driven by discs that are more gas rich, and increasingly gravitationally unstable, as a function of increasing redshift. Finally, we test two analytic models that predict turbulence is driven by either gravitational instabilities or stellar feedback. Both provide an adequate description of the data, and further observations are required to rule out either model.

Publication metadata

Author(s): Johnson HL, Harrison CM, Swinbank AM, Tiley AL, Stott JP, Bower RG, Smail I, Bunker AJ, Sobral D, Turner OJ, Best P, Bureau M, Cirasuolo M, Jarvis MJ, Magdis G, Sharples RM, Bland-Hawthorn J, Catinella B, Cortese L, Croom SM, Federrath C, Glazebrook K, Sweet SM, Bryant JJ, Goodwin M, Konstantopoulos IS, Lawrence JS, Medling AM, Owers MS, Richards S

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2018

Volume: 474

Issue: 4

Pages: 5076-5104

Print publication date: 01/03/2018

Online publication date: 23/11/2017

Acceptance date: 21/11/2017

Date deposited: 04/02/2020

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press


DOI: 10.1093/MNRAS/STX3016


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