In this Letter, we measure the rest-frame optical and near-infrared sizes of 10 quiescent candidates at 3 < z < 5, first reported by Carnall et al. We use James Webb Space Telescope Near-Infrared Camera F277W and F444W imaging obtained through the public CEERS Early Release Science program and imcascade , an astronomical fitting code that utilizes multi-Gaussian expansion, to carry out our size measurements. When compared to the extrapolation of rest-optical size–mass relations for quiescent galaxies at lower redshift, 8 out of 10 candidates in our sample (80%) are on average more compact by ∼40%. A total of 7 out of 10 candidates (70%) exhibit rest-frame infrared sizes ∼10% smaller than rest-frame optical sizes, indicative of negative color gradients. Two candidates (20%) have rest-frame infrared sizes ∼1.4× larger than rest-frame optical sizes; one of these candidates exhibits signs of ongoing or residual star formation, suggesting this galaxy may not be fully quenched. The remaining candidate is unresolved in both filters, which may indicate an active galactic nucleus. Strikingly, we observe three of the most massive galaxies in the sample (log( M ⋆ / M ⊙ ) = 10.74–10.95) are extremely compact, with effective radii ∼0.7 kpc. Our findings provide no indication that the size evolution relation flattens out, and may indicate that the size evolution of quiescent galaxies is steeper than previously anticipated beyond z > 3.

In this letter, we measure the rest-frame optical and near-infrared sizes of ten quiescent candidates at 33, even after correcting for potential color gradients. This suggests that the size evolution of quiescent galaxies is steeper than previously anticipated and our current understanding is biased by the limited wavelength capabilities of the Hubble Space Telescope (HST) and the presence of negative color gradients in quiescent galaxies.

We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at $z \geq 3$ using the Near-Infrared Camera (NIRCam) onboard $JWST$. Based on a sample selected by $UVJ$ color or $NUVUVJ$ color, we focus on 26 quiescent galaxies with $9.8<\log{(M_\star/M_\odot)}<11.4$ at $2.810.3$ implies that our size - stellar mass relations are below those at lower redshifts, with the amplitude of $\sim0.6\, {\rm kpc}$ at $M_\star = 5\times 10^{10}\, M_\odot$. This value agrees with the extrapolation from the size evolution of quiescent galaxies at $z<3$ in the literature, implying that the size of quiescent galaxies increases monotonically from $z\sim3-5$. Our sample is mainly composed of galaxies with bulge-like structures according to their median S\'ersic index and axis ratio of $n\sim3-4$ and $q\sim0.6-0.8$, respectively. On the other hand, there is a trend of increasing fraction of galaxies with low S\'ersic index, suggesting $3

REQUIEM-2D (REsolving QUIEscent Magnified galaxies with 2D grism spectroscopy) is comprised of a sample of 8 massive ($\log M_*/M_\odot > 10.6$) strongly lensed quiescent galaxies at $z\sim2$. REQUIEM-2D combines the natural magnification from strong gravitational lensing with the high spatial-resolution grism spectroscopy of \emph{Hubble Space Telescope} through a spectrophotometric fit to study spatially resolved stellar populations. We show that quiescent galaxies in the REQUIEM-2D survey have diverse formation histories manifesting as a gradient in stellar ages, including examples of (1) a younger central region supporting outside-in formation, (2) flat age gradients that show evidence for both spatially-uniform early formation or inside-out quenching, and (3) regions at a fixed radial distance having different ages (such asymmetries cannot be recovered when averaging stellar population measurements azimuthally). The typical dust attenuation curve for the REQUIEM-2D galaxies is constrained to be steeper than Calzetti's law in the UV and generally consistent with $A_V<1$. Combined together and accounting for the different physical radial distances and formation time-scales, we find that the REQUIEM-2D galaxies that formed earlier in the universe exhibit slow and uniform growth in their inner core, whereas the galaxies that formed later have rapid inner growth in their inner core with younger ages relative to the outskirts. These results challenge the currently accepted paradigm of how massive quiescent galaxies form, where the earliest galaxies are thought to form most rapidly. Significantly larger samples close to the epoch of formation with similar data quality and higher spectral resolution are required to validate this finding.