2025ApJ...985..125S

We explore the physical properties of five massive quiescent galaxies at z ∼ 2.5, revealing the presence of nonnegligible dust reservoirs. JWST NIRSpec observations were obtained for each target, finding no significant line emission; multiple star formation tracers independently place upper limits between 0.1 and 10 M_⊙ yr^–1. Spectral energy distribution modeling with Prospector infers stellar masses of ${\mathrm{log}}_{10}[M/{M}_{\odot }]\sim 10-11$ and stellar-mass-weighted ages between 1 and 2 Gyr. The inferred mass-weighted effective radii (r_eff ∼ 0.4-1.4 kpc) and inner 1 kpc stellar surface densities (${\mathrm{log}}_{10}[{\Sigma }_{\lt 1\,\mathrm{kpc}}/{M}_{\odot }\,{\mathrm{kpc}}^{2}]\gtrsim 9$) are typical of quiescent galaxies at z ≳ 2. The galaxies predominately display negative color gradients (redder core and bluer outskirts); for one galaxy, this effect results from a dusty core. Unlike local quiescent galaxies, we identify significant reddening in these typical cosmic noon passive galaxies; all but one require A_V ≳ 0.4. This finding is in qualitative agreement with previous studies, but our deep 20-band NIRCam imaging is able to significantly suppress the dust-age degeneracy and confidently determine that these galaxies are reddened. We speculate about the physical effects that may drive the decline in dust content in quiescent galaxies over cosmic time.