JWST-GO-03426: Confirming the Population of Disk Galaxies at z>3

Early deep-field images from JWST have revealed morphologies of high-redshift galaxies that suggest a surprisingly high fraction of disk galaxies at z>3. If confirmed, these results indicate that disks are able to form and settle at earlier times and lower mass scales than predicted by current cosmological simulations. However, resolved spectroscopic data is required to unambiguously confirm the presence of disk galaxies and characterize their dynamical state. We propose to use the multiplexed NIRSpec MSA in slit-stepping mode to spatially map 40-50 galaxies at z=2.4-3.6 (with 30-35 at z>3) with 3-D spectroscopy. This proposal will chart the nebular emission kinematics, allowing us to determine the true fraction of disks and their dynamical properties (in particular the degree of rotational support versus random motion, V/sigma). We will simultaneously measure resolved star formation and metallicity, to understand how the formation of galactic disks is governed by cosmological accretion and feedback. Our target selection provides good sampling across stellar masses 10^9 - 10^11 Msun, enabling us to probe mass-dependent trends at this epoch. Resolving the formation of disk galaxies at z>3 can only be achieved with JWST''s unique spatial and spectral resolution at the relevant wavelengths. This program represents a highly efficient survey of the galaxy population at this epoch, requiring a factor 25x less total integration time than the traditional IFU mode.