Title: Dynamical Constraints on Galaxy Evolution in the 1.5 Billion Years after the Big Bang

Speaker: Dr. Lilian Lee (Lai Yee Lee) （Max Planck Institute for Extraterrestrial Physics）

Time: 10:30am, March 20, 2026

Location: 3-402, PMO Xianlin Campus

Abstract: While kinematic studies at z ~ 1-3 have shown that ~70% of star-forming galaxies are regular rotating disks, the settlement of disks at higher redshifts remains uncertain due to limited high-resolution studies at z > 4 or those that exist mainly being restricted to starburst galaxies. The ALMA large program, CRISTAL, addressed this by targeting a sizeable sample of typical star-forming galaxies at 4 < z < 6, providing a clear view of their dynamical state at kpc scales. In this talk, I will first present a resolved kinematic study of 32 CRISTAL galaxies, revealing that about half of the galaxies are disk-like, a high fraction consistent with JWST morphological studies at similar cosmic epochs. These disks are characterised by strong pressure support with low V_rot/σ_0 ratio, a direct result of their gas-rich and dissipative nature. Building on this kinematic census, we probe the connection between dynamics and metal distribution using JWST IFU observations from the JWST-ALPINE-CRISTAL survey. Radial oxygen-abundance profiles, derived with strong-line diagnostics, are generally flat to slightly positive. We find a shallow anti-correlation emerges between the metallicity gradient and the V_rot/σ_0 ratio, suggesting that whether the system is rotation- or dispersion-dominated, plays a crucial role in shaping the radial metallicity gradients. The study contributes to constraints on the build-up processes and cosmic evolution of disk turbulence that also governs the radial transport of metals in the post-reionisation Universe.