Difference between Half-mass Radius and Half-light Radius of Galaxies at 0.2 &lt; <i>z</i> &lt; 2.5 Revealed by JWST/NIRCam Data

Abstract Using JWST observations in CANDELS fields, we measure the half-light radius ( r e,light ) and half-mass–radius ( r e,mass ) for 14,333 galaxies with stellar masses M * &gt; 10 9 M ⊙ at redshifts 0.2 &lt; z &lt; 2.5. To investigate the difference between r e,light and r e,mass , we find that r e,light is larger than r e,mass for both quiescent galaxies (QGs) and star-forming galaxies (SFGs). Moreover, the difference between these two radii is clearly correlated with galaxy stellar mass, r e,light , and the rest-frame U − V color. When examining the evolution of the r e,mass / r e,light ratio, we observe a significant increase for SFGs at z &gt; 1.7. In contrast, no clear increase is observed for QGs at z &gt; 1, though a slight decreasing trend is seen between 0.2 &lt; z &lt; 1.0. By fitting a linear relationship between galaxy size and stellar mass, we find that the slope for r e,light is ∼0.1–0.3 dex larger than that for r e,mass . In terms of galaxy size evolution at a fixed stellar mass, the r e,mass of QGs increases by a factor of ∼3–5 from z ∼ 2.5 to z ∼ 0.2. In contrast, the r e,mass of SFGs increases by a factor of approximately 2 over the same redshift range, with this growth trend closely following that of their r e,light . These results indicate that previous insights into galaxy evolution based on r e,light remain valid when considering r e,mass , although the specific slopes show some variations.