1 research outputs found
On the nature of disks at high redshift seen by JWST/CEERS with contrastive learning and cosmological simulations
Visual inspections of the first optical rest-frame images from JWST have
indicated a surprisingly high fraction of disk galaxies at high redshifts. Here
we alternatively apply self-supervised machine learning to explore the
morphological diversity at . Our proposed data-driven representation
scheme of galaxy morphologies, calibrated on mock images from the TNG50
simulation, is shown to be robust to noise and to correlate well with physical
properties of the simulated galaxies, including their 3D structure. We apply
the method simultaneously to F200W and F356W galaxy images of a mass-complete
sample () at from the first JWST/NIRCam CEERS data
release. We find that the simulated and observed galaxies do not populate the
same manifold in the representation space from contrastive learning, partly
because the observed galaxies tend to be more compact and more elongated than
the simulated galaxies. We also find that about half the galaxies that were
visually classified as disks based on their elongated images actually populate
a similar region of the representation space than spheroids, which according to
the TNG50 simulation is occupied by objects with low stellar specific angular
momentum and non-oblate structure. This suggests that the disk fraction at as evaluated by visual classification may be severely overestimated by
misclassifying compact, elongated galaxies as disks. Deeper imaging and/or
spectroscopic follow-ups as well as comparisons with other simulations will
help to unambiguously determine the true nature of these galaxies.Comment: 25 pages, 23 figures. Submitted to ApJ. Comments welcom