The ALPINE-CRISTAL-JWST Survey: Gas-phase abundance gradients of main sequence star-forming galaxies and their kinematics at 4<z<6

Abstract

We present gas-phase radial metallicity profiles for main-sequence galaxies at 4<z<6, primarily based on JWST NIRSpec IFU observations obtained as part of the JWST-ALPINE-CRISTAL programme. Our study aims to connect the metallicity gradients of these galaxies with their kinematic properties from [CII]158μm ALMA observations. We map the radial profiles of oxygen abundance using the strong-line method leveraging the rich set of rest-frame optical emission lines. Linear fits to the annular-binned radial profiles show that, on average, the metallicity gradients are slightly positive with a median of +0.039 +/- 0.010 dex kpc-1. There are no substantial systematic offsets in gradients when using different line diagnostics. However, only three galaxies show a gradient >0.05 dex kpc-1 at 1σ, and none have a significant negative gradient. We investigate the correlation between the metallicity gradients and the intrinsic gas velocity dispersion σ_0, as well as the ratio V_rot/σ_0 of the disks. Combining our sample with mass-matched literature samples at 3<~z<~7, we find a negative shallow correlation between V_rot /σ_0 and the metallicity gradients, but no strong relationships with σ_0. As V_rot/σ_0 increases towards later cosmic times, the observed negative trend with V_rot/σ_0 is consistent with the overall cosmic evolution of metallicity gradients from high to low redshifts. This suggests that disk maturity plays a crucial role in shaping the radial metallicity gradients. We do not find the metallicity gradients of disk galaxies significantly different from non-disk galaxies, which could be attributed to the frequent accretion events that took place in these gas-rich systems. Additionally, we find no strong dependence of metallicity gradients on stellar mass and only a marginal positive dependence on specific star-formation rate. Our study extends the efforts to connect the internal kinematics of galaxies with their gas-phase chemical enrichment at kpc scales from cosmic noon to z>4.

[Click here for the full article]