Color Gradients in Massive Quiescent Galaxies

Tue, 01 Sep 2026 00:00:00 +0000

Using JWST medium-band photometry from the MINERVA treasury survey, this project characterizes spatially resolved stellar populations in massive quiescent galaxies at z>3 — a population whose extreme early formation timescales have created significant tensions with galaxy formation models.

Cutler et al. 2026 — Color Gradients at z>3

The Astrophysical Journal Letters, doi:10.3847/2041-8213/ae960c | arXiv:2606.02698

We measure resolved photometry in a series of elliptical annuli out to 0.″7 (~4 Rₑ) for four log(M★/M☉)>11 quiescent galaxies at z>3, using MINERVA’s medium-band NIRCam imaging to track the rest-frame U − V and V − J colors as a function of radius. Three of the four galaxies show clear negative color gradients (bluer outskirts, redder cores) consistent with inside-out assembly and declining stellar ages at larger radii.

For the steepest gradient (Δ(U − V)/ΔR = −0.126 ± 0.030 mag kpc⁻¹), the inferred stellar mass is 0.1 dex lower than when measured within a fiducial NIRSpec slit, which samples only the galaxy core. Propagating this correction through extreme-value statistics models reduces the tension with ΛCDM predictions out to z ~ 9.5 — easing, though not eliminating, the too-early star formation problem.

These findings underscore the importance of integral field unit (IFU) spectroscopy for massive high-z quiescent galaxies: spatially resolved spectra are needed to break the age–dust–metallicity degeneracy and reliably disentangle the effects of color gradients from those of different physical modeling assumptions.

Resolved SED fitting with Prospector

Wed, 01 Dec 2021 00:51:36 +0000

The formation of the central parts of “typical” star-forming galaxies is an open question in astronomy. To investigate this, we present a sample of 60 z~2.3 main-sequence galaxies from the MOSFIRE Deep Evolution Field (MOSDEF) spectroscopic survey. Using the Prospector code with strong metallicity priors from MOSDEF spectra, we fit SEDs to resolved central and outer components, using a novel iterative method to robustly incorporate unresolved Spitzer/IRAC and K-band data. This technique allows us to get well-constrained, non-parametric star formation histories for the central and outer regions of these typical main-sequence galaxies (see the figure above), which provides insight into the overall assembly of star-forming galaxies.

Spatially-Resolved Modeling | Sam E. Cutler

Color Gradients in Massive Quiescent Galaxies

Cutler et al. 2026 — Color Gradients at z>3

Resolved SED fitting with Prospector