Abstract

Contributed Talk - Splinter Galaxies

Friday, 11 September 2026, 14:30   (MW-0250)

Dynamical constraints on galaxy evolution at z>4

Lilian L. Lee et al.
Max-Planck-Institut für extraterrestrische Physik

At redshifts z ~ 1–3, ~70% of star-forming galaxies are rotationally supported disks, yet the epoch when such disks first emerged is still unclear because spatially resolved observations at z>4 remain scarce. The ALMA large program CRISTAL targets [CII] emission in >30 massive star-forming galaxies at 4 < z < 6, offering an unprecedented look at their dynamics. I will present resolved kinematic studies from CRISTAL that reveal disk galaxies, which make up 50% of the population, are characterised by low rotational support with strong pressure support from gravitational processes. Building on this kinematic census, we probe the connection between dynamics and metal distribution with JWST spectroscopy. We observe radial oxygen-abundance profiles that are typically flat or mildly positive, suggesting efficient metal mixing in the systems. We find the metallicity gradients anti-correlate with the degree of rotational support from z~7 to cosmic noon, suggesting that turbulence relative to rotation plays a key role in shaping chemical distributions during early disk assembly. These results place new constraints on the emergence of rotationally supported disks and on the evolution of turbulence in high-redshift galaxies.