The ALMA-CRISTAL survey: Resolved kinematic studies of main sequence star-forming galaxies at 4 < z < 6

¹ Max-Planck-Institut für Extraterrestrische Physik (MPE), Gießenbachstra. 1, D-85748 Garching, Germany
² Departamento de Astronomía, Universidad de Concepción, Barrio Universitario, Concepción, Chile
³ Millenium Nucleus for Galaxies (MINGAL), Concepción, Chile
⁴ Purple Mountain Observatory, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing 210023, China
⁵ Space Telescope Science Institute, 3700, San Martin D, MD 21218, USA
⁶ Department of Physics and Astronomy and PITT PACC, University of Pittsburgh, Pittsburgh, PA 15260, USA
⁷ Departments of Physics and Astronomy, University of California, Berkeley, CA 94720, USA
⁸ Max-Planck-Institut für Astrophysik (MPA), Karl-Schwarzschild-Str. 1, D-85748 Garching, Germany
⁹ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, [Código Postal 8370191] Santiago, Chile
¹⁰ Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22903, USA
¹¹ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
¹² Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, UK
¹³ Universitäts-Sternwarte Ludwig-Maximilians-Universität (USM), Scheinerstr. 1, München D-81679, Germany
¹⁴ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn 3122, Australia
¹⁵ Sterrenkundig Observatorium, Ghent University, Krijgslaan 281 S9, B-9000 Ghent, Belgium
¹⁶ Institute of Astrophysics, Foundation for Research and Technology – Hellas (FORTH), Heraklion 70013, Greece
¹⁷ School of Sciences, European University Cyprus, Diogenes Street, Engomi, 1516 Nicosia, Cyprus
¹⁸ Las Campanas Observatory, Carnegie Institution of Washington, Casilla 601, La Serena, Chile
¹⁹ Department of Astronomy, School of Science, SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
²⁰ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
²¹ Department for Astrophysical & Planetary Science, University of Colorado, Boulder, CO 80309, USA
²² Department of Physics and Astronomy and George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, 4242 TAMU, College Station, TX, 77843-4242, USA
²³ Dept. Fisica Teorica y del Cosmos, E-18071 Granada, Spain
²⁴ Instituto Universitario Carlos I de Fisica Teorica y Computacional, Universidad de Granada, E-18071 Granada, Spain
²⁵ Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova I-35122, Italy
²⁶ School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
²⁷ Centre for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA
²⁸ Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605, Japan
²⁹ Department of Astronomy and Joint Space-Science Institute, University of Maryland, College Park, MD 20742, USA

^⋆ Corresponding author: lilian@mpe.mpg.de; mail@lilianlylee.com

Received: 2 May 2025
Accepted: 15 July 2025

Abstract

We present a detailed kinematic study of a sample of 32 massive (9.5 ⩽ log(M_*/M_⊙) ⩽ 10.9) main sequence star-forming galaxies (MS SFGs) at 4 < z < 6 from the ALMA-CRISTAL programme. The data consist of deep (up to 15 hr observing time per target), high-resolution (∼1 kpc) ALMA observations of [C II]158 μm line emission. This dataset allowed us to carry out the first systematic, kiloparsec-scale (kpc-scale) characterisation of the kinematics nature of typical massive SFGs at these epochs. We find that ∼50% of the sample are disk-like, with a number of galaxies located in systems of multiple components. Kinematic modelling reveals these main sequence disks exhibit high-velocity dispersions (σ₀), with a median disk velocity dispersion of ∼70 km s⁻¹ and V_rot/σ₀ ∼ 2, which is consistent with dominant gravity driving. The elevated disk dispersions are in line with the predicted evolution based on Toomre theory and the extrapolated trends from z ∼ 0–2.5 MS star-forming disks. The inferred dark matter (DM) mass fraction within the effective radius f_DM(< R_e) for the disk systems decreases with the central baryonic mass surface density. This is consistent with the trend reported by kinematic studies at z ≲ 3; roughly half the disks display f_DM(< R_e)≲ 30%. The CRISTAL sample of massive MS SFGs provides a reference of the kinematics of a representative population and extends the view onto typical galaxies beyond previous kpc-scale studies at z ≲ 3.