Lilian Lee's personal website

The ALPINE-CRISTAL-JWST Survey: Gas-phase abundance gradients of main sequence star-forming galaxies and their kinematics at 4
Tue, 07 Oct 2025 22:40:32 GMT

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.

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

Mon, 01 Sep 2025 23:46:37 GMT

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 Vrot/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 fDM(< Re) 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 fDM(< Re)≲ 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.

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Key Figures

Figure 1. Velocity fields of the CRISTAL sources.

Figure 2. Redshift evolution of rotational support of disk galaxies.

Disk Kinematics at High Redshift: DysmalPy's Extension to 3D Modeling and Comparison with Different Approaches

Wed, 01 Jan 2025 22:40:32 GMT

Abstract

Spatially resolved emission-line kinematics are invaluable for investigating fundamental galaxy properties and have become increasingly accessible for galaxies at z ≳0.5 through sensitive near-infrared imaging spectroscopy and millimeter interferometry. Kinematic modeling is at the core of the analysis and interpretation of such data sets, which at high z present challenges due to the lower signal-to-noise ratio (S/N) and resolution compared to the data of local galaxies. We present and test the 3D fitting functionality of DysmalPy, examining how well it recovers the intrinsic disk rotation velocity and velocity dispersion, using a large suite of axisymmetric models, covering a range of galaxy properties and observational parameters typical of z ∼ 1‑3 star-forming galaxies. We also compare DysmalPy’s recovery performance to that of two other commonly used codes, GalPak 3D and 3D Barolo, which we use in turn to create additional sets of models to benchmark DysmalPy. Over the ranges of S/N, resolution, mass, and velocity dispersion explored, the rotation velocity is accurately recovered by all tools. The velocity dispersion is recovered well at high S/N, but the impact of methodology differences is more apparent. In particular, template differences for parametric tools and S/N sensitivity for the nonparametric tool can lead to differences of up to a factor of 2. Our tests highlight and the importance of deep, high-resolution data and the need for careful consideration of (i) the choice of priors (parametric approaches); and (ii) the masking (all approaches); and (iii), more generally, the evaluating of the suitability of each approach to the specific data at hand. This paper accompanies the public release of DysmalPy.

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Key Figure