James Webb Space Telescope Feed Post


Literature
Date: 8/20/2024

Arxiv: The Size-Mass relation at Rest-Frame 1.5μm from JWST/NIRCam in the COSMOS-WEB and PRIMER-COSMOS fields Published: 6/25/2024 8:41:53 PM Updated: 8/19/2024 1:27:09 PM


Paper abstract: We present the galaxy stellar mass - size relation in the rest-frame near-IR(1.5~\mu{\text{m}}) and its evolution with redshift up to z=2.5. S\'ersicprofiles are measured for ~ 26\,000 galaxies with stellar massesM_* > 10^9~{\text{M}}_\odot from JWST/NIRCam F277W and F444W imagingprovided by the COSMOS-WEB and PRIMER surveys, using coordinates, redshifts,colors and stellar mass estimates from the COSMOS2020 catalog. The newrest-frame near-IR effective radii are generally smaller than previouslymeasured rest-frame optical sizes, on average by 0.14~dex, with no significantdependence on redshift. For quiescent galaxies this size offset does not dependon stellar mass, but for star-forming galaxies the offset increases from-0.1~dex at M_* = 10^{9.5}~{\text{M}}_\odot to -0.25~dex at M_* >10^{11}~{\text{M}}_\odot. That is, we find that the near-IR stellar mass -size relation for star-forming galaxies is flatter in the rest-frame near-IRthan in the rest-frame optical at all redshifts 0.510^{11}~{\text{M}}_\odot) star-forming galaxies evolve in sizealmost as fast as quiescent galaxies. Low-mass(M_*<10^{10}~{\text{M}}_\odot)~quiescent galaxies evolve as slow asstar-forming galaxies. Our main conclusion is that the size evolution narrativeas it has emerged over the past two decades does not radically change whenaccessing with JWST the rest-frame near-IR, a better proxy of the underlyingstellar mass distribution.