Evolution and Mass Dependence of UV-to-near-IR Color Gradients up to z=2.5 from HST+JWST

Abstract

We present the redshift evolution of radial color gradients (in rest-frame $\text{U}-\text{V}$ and $\text{V}-\text{J}$) for galaxies in the range $0.5<$ z $<2.5$ and investigate their origin and dependence on stellar mass. We select $\sim 10,200$ galaxies with stellar masses $M_{\star }>10^{9.5}{\text{M}}_{\odot }$ from publicly available JWST/NIRCam-selected catalogs. Using 2D Sérsic profile fits to account for PSF broadening, we perform spatially resolved SED fitting on HST and JWST/NIRCam photometry retrieving accurate rest-frame $\text{U}-\text{V}$ and $\text{V}-\text{J}$ color gradients within 2$R_{\text{e, F444W}}$. Star-forming galaxies generally exhibit negative $\text{V}-\text{J}$ color gradients that are strongly mass and redshift dependent. For massive star-forming galaxies ($M_{\star }>10^{10.5}{\text{M}}_{\odot }$) at $z>1.5$ $\text{V}-\text{J}$ colors are $\approx 0.5$ mag redder within the effective radius than outside, on average. We find that, at all redshifts and across the entire stellar mass range, $\text{V}-\text{J}$ gradients strongly correlate with global attenuation ($A_V$), suggesting 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 $\text{U}-\text{V}$ and $\text{V}-\text{J}$ color gradients in the quiescent galaxy population, in contrast, are weakly negative (from $\approx -0.1$ to $\approx -0.2$ mag), though significant, and show little or no dependence on stellar mass, redshift or axis ratio. The implication is that quiescent galaxies must be largely transparent, with low $A_V$, and color gradients mostly attributable to stellar population gradients.

Accepted for publication on A&A; 12 pages with 8 figures, 4 pages appendix with 3 figures