Morphological and Star Formation Properties of Cosmic Noon Massive Quiescent Galaxies

Abstract

We analyze the star formation and morphological properties of massive quiescent galaxies at cosmic noon (2 < z < 3) in the A2744 field, using deep JWST/NIRCam broadband and medium-band imaging from the UNCOVER Treasury program and the MegaScience survey, complemented by archival Hubble Space Telescope data. Using BAGPIPES spectral energy distribution (SED) modeling, we select 14 unique massive quiescent galaxies (M* ≳ 1010 M⊙; specific star formation rate (sSFR) < 0.2/tage). Morphological analysis with statmorph and pysersic reveals that most galaxies are intermediate type or S0s with a median Sérsic index n ∼ 4, consistent with bulge-dominated systems. This value remains constant over z ∼ 1.5–4, indicating that the morphology of massive galaxies is linked to their quiescence since at least z ∼ 4. Spatially resolved SED modeling with piXedfit shows that 11 out of 14 galaxies exhibit positive radial sSFR gradients, providing direct evidence for inside-out quenching, with the mean sSFR increasing by ∼2 dex from R/Re = 0.5–4.5. Formation time (t50) profiles confirm that inner regions formed ≈0.5 Gyr earlier, on average, than the outer regions, and quenching timescale profiles show that the cores were quenched more rapidly than the outskirts. Most galaxies are compact, with a mean half-mass radius of Re = 1.95 ± 0.13 kpc. The observed inside-out quenching pattern is consistent with quenching driven by active galactic nucleus feedback, while the bulge-dominated morphologies suggest morphological quenching may also contribute.