Stellar Half-Mass Radii of $0.5<z<2.3$ Galaxies: Comparison with JWST/NIRCam Half-Light Radii

Abstract

We use CEERS JWST/NIRCam imaging to measure rest-frame near-IR light profiles of $>$500 $M_{\star }>10^{10}{M}_{\odot }$ galaxies in the redshift range $0.5<z<2.3$. We compare the resulting rest-frame 1.5-2$\mu$m half-light radii ($R_{\mathrm{NIR}}$) with stellar half-mass radii (\rmass) derived with multi-color light profiles from CANDELS HST imaging. In general agreement with previous work, we find that $R_{\mathrm{NIR}}$ and \rmass~are up to 40\%~smaller than the rest-frame optical half-light radius $R_{\mathrm{opt}}$. The agreement between $R_{\mathrm{NIR}}$ and \rmass~is excellent, with negligible systematic offset ($<$0.03 dex) up to $z=2$ for quiescent galaxies and up to $z=1.5$ for star-forming galaxies. We also deproject the profiles to estimate \rmassd, the radius of a sphere containing 50\% of the stellar mass. We present the $R-M_{\star }$ distribution of galaxies at $0.5<z<1.5$, comparing $R_{\mathrm{opt}}$, \rmass~and \rmassd. The slope is significantly flatter for \rmass~and \rmassd~ compared to $R_{\mathrm{opt}}$, mostly due to downward shifts in size for massive star-forming galaxies, while \rmass~and \rmassd~do not show markedly different trends. Finally, we show rapid size evolution ($R\propto (1+z{)}^{-1.7\pm 0.1}$) for massive ($M_{\star }>10^{11}{M}_{\odot }$) quiescent galaxies between $z=0.5$ and $z=2.3$, again comparing $R_{\mathrm{opt}}$, \rmass~and \rmassd. We conclude that the main tenets of the size evolution narrative established over the past 20 years, based on rest-frame optical light profile analysis, still hold in the era of JWST/NIRCam observations in the rest-frame near-IR.

Submitted to ApJ. Comments welcome