2025/04/09 by Yang, Lilan, Kartaltepe, Jeyhan S., Franco, Maximilien +26 · 3 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2504.07185
We measure galaxy sizes from 2 < z < 10 using COSMOS-Web, the largest-area JWST imaging survey to date, covering ∼0.54 deg2. We analyze the rest-frame optical (~5000A) size evolution and its scaling relation with stellar mass (Re∝ M_*α) for star-forming and quiescent galaxies. For star-forming galaxies, the slope α remains approximately 0.20 at 2 < z < 8, showing no significant evolution over this redshift range. At higher redshifts, the slopes are -0.13 ± 0.15 and 0.37 ± 0.36 for 8 < z < 9 and 9 < z < 10, respectively. At fixed galaxy mass, the size evolution for star-forming galaxies follows Re ∝ (1+z)-β, with β= 1.21 ± 0.05. For quiescent galaxies, the slope is steeper α∼ 0.5-0.8 at 2 < z < 5, and β=0.81±0.26. We find that the size-mass relation is consistent between UV and optical at z < 8 for star-forming galaxies. However, we observe a decrease in the slope from UV to optical at z > 8, with a tentative negative slope in the optical at 8 < z < 9, suggesting a complex interplay between intrinsic galaxy properties and observational effects such as dust attenuation. We discuss the ratio between galaxies' half-light radius, and underlying halos' virial radius, Rvir, and find the median value of Re/Rvir=2.7%. The star formation rate surface density evolves as logΣSFR = (0.20±0.08) z+(-0.65±0.51), and the ΣSFR-M_* relation remains flat at 2 3 provides new insights into galaxy size and related properties in the rest-frame optical.