  With the remarkable sensitivity and resolution of JWST in the infrared,
measuring rest-optical kinematics of galaxies at $z>5$ has become possible for
the first time. This study pilots a new method for measuring galaxy dynamics
for highly multiplexed, unbiased samples by combining FRESCO NIRCam grism
spectroscopy and JADES medium-band imaging. Here we present one of the first
JWST kinematic measurements for a galaxy at $z>5$. We find a significant
velocity gradient, which, if interpreted as rotation yields $V_{rot} =
240\pm50$km/s and we hence refer to this galaxy as Twister-z5. With a
rest-frame optical effective radius of $r_e=2.25$kpc, the high rotation
velocity in this galaxy is not due to a compact size as may be expected in the
early universe but rather a high total mass, ${\rm log(M}_{dyn}/{\rm
M}_\odot)=11.0\pm0.2$. This is a factor of roughly 4x higher than the stellar
mass within the effective radius. We also observe that the radial H$\alpha$
equivalent width profile and the specific star formation rate map from resolved
stellar population modeling is centrally depressed by a factor of $\sim1.5$
from the center to $r_e$. Combined with the morphology of the line-emitting gas
in comparison to the continuum, this centrally suppressed star formation is
consistent with a star-forming disk surrounding a bulge growing inside-out.
While large, rapidly rotating disks are common to z~2, the existence of one
after only 1Gyr of cosmic time, shown for the first time in ionized gas, adds
to the growing evidence that some galaxies matured earlier than expected in the
history of the universe.

Astrophysics of Galaxies