Kavli Affiliate: Jinyi Shangguan
| First 5 Authors: Juan M. Espejo Salcedo, Stavros Pastras, Josef Vácha, Claudia Pulsoni, Reinhard Genzel
| Summary:
The way in which radial flows shape galaxy structure and evolution remains an
open question. Internal drivers of such flows, such as bars and spiral arms,
known to mediate gas flows in the local Universe, are now observable at high
redshift thanks to JWST’s unobscured view. We investigated the morphology of
massive star-forming galaxies at 0.8<z<1.3 and 2.0<z<2.5, epochs marking the
peak and decline of cosmic star formation, both well covered by kinematic
surveys. Using JWST/NIRCam imaging, we visually classified 1,451 galaxies,
identified nonaxisymmetric features, counted the number of spiral arms,
analyzed nonparametric morphological indicators, and studied the dynamical
support of the sample covered by kinematics ($approx$ 11% of the sample) as
measured via $v/sigma$. Disks dominate the sample (fraction $0.82 pm 0.03$);
among them, $0.48 pm 0.04$ exhibit spiral structure and $0.11 pm 0.03$ host
bars. Both fractions decline with redshift, in agreement with previous studies.
The proportion of two- and three-armed spirals remains largely unchanged across
our redshift bins: approximately two-thirds show two arms and one-third show
three arms in both bins. Notably, we find a higher incidence of three-armed
spirals ($approx 0.30$) than reported in the local Universe ($approx 0.20$),
suggesting a mild evolution in spiral arm multiplicity. Nonparametric
morphological metrics strongly correlate with stellar mass but show no
significant redshift evolution. Finally, kinematic analysis reveals a
correlation between disk morphology and rotational support: most disks exhibit
$v/sigma > 3$ and median values of $v/sigma > 7$ for spirals and $v/sigma >
5$ for barred galaxies. This study establishes a population-wide framework for
linking galaxy morphology and dynamics at cosmic noon, providing a key
reference for future studies on the role of detailed structural features in
galaxy evolution.
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