2026ApJ...998..229X -
Astrophys. J., 998, 229 (2026/February-3)
Difference between Half-mass Radius and Half-light Radius of Galaxies at 0.2 < z < 2.5 Revealed by JWST/NIRCam Data.
XIN M., FANG G., SONG J., LU S., LIN Z. and KONG X.
Abstract (from CDS):
Using JWST observations in CANDELS fields, we measure the half-light radius (re,light) and half-mass-radius (re,mass) for 14,333 galaxies with stellar masses M* > 109M_⊙ _at redshifts 0.2 < z < 2.5. To investigate the difference between re,light and re,mass, we find that re,light is larger than re,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, re,light, and the rest-frame U - V color. When examining the evolution of the re,mass/re,light ratio, we observe a significant increase for SFGs at z > 1.7. In contrast, no clear increase is observed for QGs at z > 1, though a slight decreasing trend is seen between 0.2 < z < 1.0. By fitting a linear relationship between galaxy size and stellar mass, we find that the slope for re,light is ∼0.1-0.3 dex larger than that for re,mass. In terms of galaxy size evolution at a fixed stellar mass, the re,mass of QGs increases by a factor of ∼3-5 from z ∼ 2.5 to z ∼ 0.2. In contrast, the re,mass of SFGs increases by a factor of approximately 2 over the same redshift range, with this growth trend closely following that of their re,light. These results indicate that previous insights into galaxy evolution based on re,light remain valid when considering re,mass, although the specific slopes show some variations.
Abstract Copyright:
© 2026. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Galaxy evolution - Galaxy formation - Galaxy radii
Simbad objects:
4
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