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The KMOS Redshift One Spectroscopic Survey (KROSS): dynamical properties, gas and dark matter fractions of typical z~1 star-forming galaxies

Stott, J.P.; Swinbank, A.M.; Johnson, H.L.; Tiley, A.; Magdis, G.; Bower, R.; Bunker, A.J.; Bureau, M.; Harrison, C.M.; Jarvis, M.J.; Sharples, R.; Smail, I.; Sobral, D.; Best, P.; Cirasuolo, M.

The KMOS Redshift One Spectroscopic Survey (KROSS): dynamical properties, gas and dark matter fractions of typical z~1 star-forming galaxies Thumbnail


Authors

J.P. Stott

H.L. Johnson

A. Tiley

G. Magdis

R. Bower

A.J. Bunker

M. Bureau

C.M. Harrison

M.J. Jarvis

D. Sobral

P. Best

M. Cirasuolo



Abstract

The KMOS Redshift One Spectroscopic Survey (KROSS) is an ESO-guaranteed time survey of 795 typical star-forming galaxies in the redshift range z = 0.8–1.0 with the KMOS instrument on the Very Large Telescope. In this paper, we present resolved kinematics and star formation rates for 584 z ∼ 1 galaxies. This constitutes the largest near-infrared Integral Field Unit survey of galaxies at z ∼ 1 to date. We demonstrate the success of our selection criteria with 90 per cent of our targets found to be H α emitters, of which 81 per cent are spatially resolved. The fraction of the resolved KROSS sample with dynamics dominated by ordered rotation is found to be 83 ± 5 per cent. However, when compared with local samples these are turbulent discs with high gas to baryonic mass fractions, ∼35 per cent, and the majority are consistent with being marginally unstable (Toomre Q ∼ 1). There is no strong correlation between galaxy averaged velocity dispersion and the total star formation rate, suggesting that feedback from star formation is not the origin of the elevated turbulence. We postulate that it is the ubiquity of high (likely molecular) gas fractions and the associated gravitational instabilities that drive the elevated star formation rates in these typical z ∼ 1 galaxies, leading to the 10-fold enhanced star formation rate density. Finally, by comparing the gas masses obtained from inverting the star formation law with the dynamical and stellar masses, we infer an average dark matter to total mass fraction within 2.2re (9.5 kpc) of 65 ± 12 per cent, in agreement with the results from hydrodynamic simulations of galaxy formation.

Citation

Stott, J., Swinbank, A., Johnson, H., Tiley, A., Magdis, G., Bower, R., …Cirasuolo, M. (2016). The KMOS Redshift One Spectroscopic Survey (KROSS): dynamical properties, gas and dark matter fractions of typical z~1 star-forming galaxies. Monthly Notices of the Royal Astronomical Society, 457(2), 1888-1904. https://doi.org/10.1093/mnras/stw129

Journal Article Type Article
Acceptance Date Jan 13, 2016
Online Publication Date Feb 4, 2016
Publication Date Apr 1, 2016
Deposit Date Feb 9, 2016
Publicly Available Date Feb 9, 2016
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 457
Issue 2
Pages 1888-1904
DOI https://doi.org/10.1093/mnras/stw129
Keywords Galaxies: evolution, Galaxies: kinematics and dynamics, Galaxies: star formation.
Public URL https://durham-repository.worktribe.com/output/1389452
Related Public URLs http://adsabs.harvard.edu/abs/2016MNRAS.457.1888S

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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