Galaxy morphology from z ∼ 6 through the lens of JWST
Wuyts, S.; Elbaz, D.; Dickinson, M.; Finkelstein, S. L.; Papovich, C.; Koekemoer, A. M.; Huertas-Company, M.; Kartaltepe, J.; Behroozi, P.; Dekel, A.; Lucas, R. A.; Grogin, N. A.; Hathi, N. P.; Yang, G.; Holwerda, B. W.; Arrabal Haro, P.; Bagley, M. B.; Cheng, Y.; Pérez-González, P. G.; de la Vega, A.; Yung, L. Y. A.; Buitrago, F.; Pirzkal, N.; Costantin, L.; McGrath, E. J.; Iyer, K. G.; Angeloudi, E.; Sarmiento, R.; Vega-Ferrero, J.; Seillé, L. -M.
Spain, France, United States, Japan, Portugal, Israel, United Kingdom, Netherlands
Abstract
Context. The James Webb Space Telescope's (JWST's) unprecedented combination of sensitivity, spatial resolution, and infrared coverage has enabled a new era of galaxy morphology exploration across most of cosmic history.
Aims: We analyze the near-infrared (NIR ∼ 0.8 − 1 μm) rest-frame morphologies of galaxies with log M*/M⊙ > 9 in the redshift range of 0 < z < 6, compare with previous HST-based results and release the first JWST-based morphological catalog of ∼20 000 galaxies in the CEERS survey.
Methods: We classified the galaxies in our sample into four main broad classes: spheroid, disk+spheroid, disk, and disturbed, based on imaging with four filters: F150W, F200W, F356W, and F444W. We used convolutional neural networks (CNNs) trained on HST/WFC3 labeled images and domain-adapted to JWST/NIRCam.
Results: We find that ∼90% and ∼75% of galaxies at z < 3 have the same early and late and regular and irregular classification, respectively, in JWST and HST imaging when considering similar wavelengths. For small (large) and faint objects, JWST-based classifications tend to systematically present less bulge-dominated systems (peculiar galaxies) than HST-based ones, but the impact on the reported evolution of morphological fractions is less than ∼10%. Using JWST-based morphologies at the same rest-frame wavelength (∼0.8 − 1 μm), we confirm an increase in peculiar galaxies and a decrease in bulge-dominated galaxies with redshift, as reported in previous HST-based works, suggesting that the stellar mass distribution, in addition to light distribution, is more disturbed in the early Universe. However, we find that undisturbed disk-like systems already dominate the high-mass end of the late-type galaxy population (log M*/M⊙ > 10.5) at z ∼ 5, and bulge-dominated galaxies also exist at these early epochs, confirming a rich and evolved morphological diversity of galaxies ∼1 Gyr after the Big Bang. Finally, we find that the morphology-quenching relation is already in place for massive galaxies at z > 3, with massive quiescent galaxies (log M*/M⊙ > 10.5) being predominantly bulge-dominated.