NOEMA 3D : Resolving radial gas flows in disk galaxies at z ~ 1.1–1.6 with high-resolution CO observations

We present NOEMA 3D , a unique high-resolution study of purely molecular gas kinematics at z ~ 1.1 to 1.6, providing a dedicated view of cold gas dynamics at the late stages of the peak epoch of cosmic star formation. Using deep (≳20 h on source per target) IRAM–NOEMA CO observations of ten massive (10.45 ≤ log(M ⋆ /M ⊙ ) ≤ 11.43) main-sequence galaxies, complemented by high-resolution JWST imaging, we resolved the molecular gas kinematics and morphology on kiloparsec scales. We find that all galaxies exhibit ordered rotation with moderate intrinsic turbulence (median σ 0 ~ 32 ± 10 km s −1 , median V c / σ 0 ~ 8.6 ± 2.9), consistent with dynamically turbulent disks at late cosmic noon. Modeling the axisymmetric rotation with the forward-modeling code DysmalPy , we find spatially coherent velocity residuals in all but one edge-on system. The inferred in-plane noncircular motions reach amplitudes of ~50–100 km s −1 , which are significantly larger than typically observed in local disk galaxies. Interpreting these noncircular motions as radial flows, we find that the velocity residuals spatially coincide with non-axisymmetric structures - spiral arms and bars – demonstrating a direct link between galaxy morphology and gas transport at z ~ 1–2. In spiral galaxies, the residual velocity patterns are typically dominated by inflows, while barred systems display an apparent inflow-outflow pattern, characteristic of in-plane bar-driven gas motions. We further find that the inferred molecular gas inflow rates are substantial, with a typical net inflow rate on the order of the star formation rate ( M ˙¯ ~ −46M ⊙ /yr). This implies that spiral arms and bars at cosmic noon are highly efficient at funneling cold gas toward galaxy centers, perhaps driving the buildup of bulges and feeding central star forming regions and supermassive black holes.