Morphological and Star Formation Properties of Cosmic Noon Massive Quiescent Galaxies

TL;DR

This study investigates the morphology and star formation cessation patterns of massive quiescent galaxies at cosmic noon ($2<z<3$) using JWST and HST data, revealing inside-out quenching and bulge-dominated structures.

Contribution

It provides the first detailed spatially resolved analysis of quenching and morphology for massive galaxies at $z\, ext{~}2$–$3$, linking quiescence to morphology since $z\, ext{~}4$.

Findings

Most galaxies are bulge-dominated with Sersic index $\, ext{~}4$.

79 ext{ extbackslash}% of galaxies show positive sSFR gradients, indicating inside-out quenching.

Inner regions formed earlier and quenched faster than outer regions.

Abstract

We analyze the star formation and morphological properties of massive quiescent galaxies at cosmic noon ($2 < z < 3$) in the Abell 2744 field, using deep JWST NIRCam broad-band and medium-band imaging from the UNCOVER Treasury program and the MegaScience survey, complemented by archival HST data. Using BAGPIPES SED modeling, we select 14 unique massive quiescent galaxies ($M_* \gtrsim 10^{10}$ M$_\odot$, $\mathrm{sSFR} < 0.2/t_\mathrm{age}$). Morphological analysis with statmorph and pysersic reveals that most galaxies are intermediate type or S0s with a median S\'ersic index $n \sim 4$, consistent with bulge-dominated systems. This value remains constant over $z \sim 1.5$--$4$, indicating that the morphology of massive galaxies is linked to their quiescence since at least $z \sim 4$. Spatially resolved SED modeling with piXedfit shows that $\sim 79\%$ of galaxies exhibit positive radial sSFR gradients, providing direct evidence for inside-out quenching, with the mean sSFR increasing by $\sim2$ dex from $R/R_e = 0.5$ to $4.5$. Formation time ($t_{50}$) profiles confirm that inner regions formed $\approx 0.5$ Gyr earlier, on average, than the outer regions, and quenching timescale profiles show that the cores were quenched more rapidly than the outskirts. Some galaxies show weak indications of possible AGN activity. Most galaxies are compact, with a mean half-mass radius of $R_e = 1.95 \pm 0.13$ kpc. The observed inside-out quenching pattern and possible AGN signatures are consistent with AGN feedback playing a role in star formation cessation, while the bulge-dominated morphologies suggest morphological quenching may also contribute.