KURVS: the outer rotation curve shapes and dark matter fractions of z ∼1.5 star-forming galaxies
Journal article, 2023
We present first results from the KMOS Ultra-deep Rotation Velocity Survey (KURVS), aimed at studying the outer rotation curves shape and dark matter content of 22 star-forming galaxies at z ∼1.5. These galaxies represent 'typical' star-forming discs at z ∼1.5, being located within the star-forming main sequence and stellar mass-size relation with stellar masses 9.5 ≤ log(M*/M⊙) ≤ 11.5. We use the spatially resolved H α emission to extract individual rotation curves out to 4 times the effective radius, on average, or ∼10-15 kpc. Most rotation curves are flat or rising between three and six disc scale radii. Only three objects with dispersion-dominated dynamics (vrot/σ0 ∼0.2) have declining outer rotation curves at more than 5σ significance. After accounting for seeing and pressure support, the nine rotation-dominated discs with vrot/σ0 ≥ 1.5 have average dark matter fractions of at the effective radius, similar to local discs. Together with previous observations of star-forming galaxies at cosmic noon, our measurements suggest a trend of declining dark matter fraction with increasing stellar mass and stellar mass surface density at the effective radius. Measurements of simulated EAGLE galaxies are in quantitative agreement with observations up to log, and overpredict the dark matter fraction of galaxies with higher mass surface densities by a factor of ∼3. We conclude that the dynamics of typical rotationally-supported discs at z ∼1.5 is dominated by dark matter from effective radius scales, in broad agreement with cosmological models. The tension with observations at high stellar mass surface density suggests that the prescriptions for baryonic processes occurring in the most massive galaxies (such as bulge growth and quenching) need to be reassessed.
galaxies: high-redshift
galaxies: kinematics and dynamics
galaxies: evolution
Author
A. Puglisi
Durham University
University of Southampton
U. Dudzeviciute
Max Planck Society
Mark Swinbank
Durham University
S. Gillman
Cosmic Dawn Center (DAWN)
Technical University of Denmark (DTU)
Alfred L. Tiley
Durham University
University of Western Australia
Richard G. Bower
Durham University
Michele Cirasuolo
European Southern Observatory (ESO)
Luca Cortese
University of Western Australia
ARC Centre of Excellence for All-sky Astrophysics
Karl Glazebrook
Swinburne University of Technology
C. M. Harrison
Newcastle University
E. Ibar
University of Valparaíso
Juan Andrés Molina Tobar
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Danail Obreschkow
University of Western Australia
ARC Centre of Excellence for All-sky Astrophysics
Kyle A. Oman
Durham University
Matthieu Schaller
Instituut-Lorentz for Theoretical Physics, Leiden
Leiden University
F. Shankar
University of Southampton
R. Sharples
Durham University
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 524 2 2814-2835Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/stad1966