Evolution and mass dependence of UV-to-near-IR color gradients up to z = 2.5 from the Hubble Space Telescope and the James Webb Space Telescope

¹ Sterrenkundig Observatorium, Universiteit Gent Krijgslaan 281 S9 9000 Gent, Belgium
² Department of Astronomy, University of Michigan 1085 South University Avenue Ann Arbor MI 48109–1107, USA
³ Cosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen Jagtvej 128 København N DK-2200, Denmark
⁴ STAR Institute, Université de Liège, Quartier Agora Allée du Six Aout 19c B-4000 Liege, Belgium
⁵ Department of Astronomy, University of Massachusetts Amherst MA 01003, USA
⁶ Department of Physics, University of Bath, Claverton Down Bath BA2 7AY, UK

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 16 June 2025
Accepted: 28 November 2025

Abstract

Aims. We present the redshift evolution of radial color gradients (in rest-frame U − V and V − J) for galaxies in the range 0.5 < z < 2.5 and investigate their origin and the dependence on stellar mass.

Methods. We selected ≈10 200 galaxies with stellar masses M_★ > 10^9.5 M_⊙ from publicly available JWST/NIRCam-selected catalogs. Using 2D Sérsic profile fits to account for point spread function broadening, we performed a spatially resolved spectral energy distribution fitting on HST and JWST/NIRCam photometry to retrieve accurate rest-frame U − V and V − J color gradients within 2 R_e, F444W.

Results. The generally negative V − J color gradients of star-forming galaxies strongly depend on mass and redshift. For massive star-forming galaxies (M_★ > 10^10.5 M_⊙) at z > 1.5, the V − J colors are ≈0.5 mag redder within the effective radius than outside on average. At all redshifts and throughout the entire stellar mass range, the V − J gradients strongly correlate with global attenuation (A_V), which suggests that they predominantly trace dust attenuation gradients. Edge-on galaxies are redder and have stronger gradients at all z, although the correlation weakens at higher z. The U − V and V − J color gradients in the quiescent galaxy population, in contrast, are weakly negative (from ≈ − 0.1 to ≈ − 0.2 mag) but significant, and they depend little or not at all on stellar mass, redshift, or axis ratio. The implication is that quiescent galaxies must be largely transparent, with low A_V, and their color gradients are mostly attributable to stellar population gradients.