Regular rotation and low turbulence in a diverse sample of <i>z</i> ∼ 4.5 galaxies observed with ALMA

ABSTRACT The discovery of galaxies with regularly rotating discs at redshifts ≥4 has been a puzzling challenge to galaxy formation models that tend predict chaotic gas kinematics in the early Universe as consequence accretion, mergers, and efficient feedback. In this work, we investigated five highly resolved z ∼ 4.5 observed ALMA [C ii] 158 $\mu$m emission line. sample is diverse: AzTEC1 (starburst galaxy), BRI1335-0417 quasar host J081740 (normal star-forming SGP38326 (two starburst group). show velocity gradients, but four were found be discs, while remaining, AzTEC1, likely merger. We studied using 3DBAROLO they rotate maximum rotation velocities between 198 562 km s−1, dispersions, averaged across are 49 75 s−1. curves generally flat have ratios ordered-to-random motion (V/σ) 2.7 9.8. present CANNUBI, an algorithm for fitting disc geometry 3D emission-line observations prior modelling kinematics, which find indications these may thicknesses order 1 kpc. This study shows clear dominance respect turbulent motions variety types.