Toggle Main Menu Toggle Search

Open Access padlockePrints

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

Lookup NU author(s): Dr Christopher HarrisonORCiD


Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


© 2016 The Authors. 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 Hα 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.

Publication metadata

Author(s): Stott JP, Swinbank AM, Johnson HL, Tiley A, Magdis G, Bower R, Bunker AJ, Bureau M, Harrison CM, Jarvis MJ, Sharples R, Smail I, Sobral D, Best P, Cirasuolo M

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2016

Volume: 457

Issue: 2

Pages: 1888-1904

Print publication date: 01/04/2016

Online publication date: 04/02/2016

Acceptance date: 13/01/2016

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press


DOI: 10.1093/mnras/stw129


Altmetrics provided by Altmetric