2026ApJ...998..248B

We present the neutral gas morphology of four galaxies from z = 0.22 to 0.47 obtained with the COSMOS HI Large Extragalactic Survey (CHILES). The H I is resolved at the highest redshift with the 7$\mathop{.}\limits^{\unicode{x02033}}$5 beam of CHILES and 43 kpc linear scale, with all four galaxies having extended H I. Three are massive galaxies (M_* > 3 × 10¹⁰M_⊙), with H I masses of (1.6-6.7) × 10¹⁰M_⊙ and active star formation (3-30 M_⊙ yr^–1). The morphology and kinematics of the galaxies vary from regular to disturbed, including an asymmetric H I disk surrounding the fourth smaller galaxy (M_* ∼ 10⁹M_⊙). CO (1-0) observations of the sample, obtained with the Large Millimeter Telescope, confirm the redshifts of three of the four galaxies, and we derive H₂ masses of (0.4-5.2) × 10¹⁰M_⊙. JWST imaging with four combined NIRCam filters reveals disturbed stellar components with compact knots in two of the galaxies. We combine our new higher-redshift galaxies with previously published observations to conduct a more complete study of H I and H₂ evolution in the redshift range 0-0.5. With our H I flux-limited observations compared to similar lower-redshift galaxies with high stellar mass (M_* > 10¹⁰M_⊙), the results show that the mean H₂/H I ratio at the highest redshift is 10.3 ± 3.4, larger than the mean H₂/H I ratio in the local Universe.