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Arxiv: Morphology of Galaxies in JWST Fields: Initial Distribution and Evolution of Galaxy Morphology Published: 12/8/2023 10:30:10 AM Updated: 3/14/2024 5:51:29 AM

Paper abstract: A recent study from the Horizon Run (HR5) cosmological simulation haspredicted that galaxies with {\rm log}~M_{\ast}/M_{\odot}<~ 10 in thecosmic morning (10\gtrsim z\gtrsim 4) dominantly have disk-like morphology inthe \LambdaCDM universe, which is driven by the tidal torque in the initialmatter fluctuations. For a direct comparison with observation, we identify atotal of about 19,000 James Webb Space Telescope (JWST) galaxies with {\rmlog}~M_{\ast}/M_{\odot}>9 at z=0.6-8.0 utilizing deep JWST/NIRCam images ofpublicly released fields, including NEP-TDF, NGDEEP, CEERS, COSMOS, UDS, andSMACS J0723-7327. We estimate their stellar masses and photometric redshiftswith the redshift dispersion of \sigma_{\rm NMAD}=0.009 and outlier fractionof only about 6\%. We classify galaxies into three morphological types,`disks', `spheroids', and `irregulars', applying the same criteria used in theHR5 study. The morphological distribution of the JWST galaxies shows that diskgalaxies account for 60-70\% at all redshift ranges. However, in thehigh-mass regime ({\rm log}~M_{\ast}/M_{\odot}\gtrsim11), spheroidalmorphology becomes the dominant type. This implies that mass growth of galaxiesis accompanied with morphological transition from disks to spheroids. Thefraction of irregulars is about 20\% or less at all mass and redshifts. All thetrends in the morphology distribution are consistently found in the six JWSTfields. These results are in close agreement with the results from the HR5simulation, particularly confirming the prevalence of disk galaxies at smallmasses in the cosmic morning and noon.