JADES: Rest-frame UV-to-NIR Size Evolution of Massive Quiescent Galaxies from Redshift z=5 to z=0.5
Zhiyuan Ji, Christina C. Williams, Katherine A. Suess, Sandro Tacchella, Benjamin D. Johnson, Brant Robertson, Stacey Alberts, William M. Baker, Stefi Baum, Rachana Bhatawdekar, Nina Bonaventura, Kristan Boyett, Andrew J. Bunker, Stefano Carniani, Stephane Charlot, Zuyi Chen, Jacopo Chevallard, Emma Curtis-Lake, Francesco D'Eugenio, Anna de Graaff, Christa DeCoursey, Eiichi Egami, Daniel J. Eisenstein, Kevin Hainline, Ryan Hausen, Jakob M. Helton, Tobias J. Looser, Jianwei Lyu, Roberto Maiolino, Michael V. Maseda, Erica Nelson, George Rieke, Marcia Rieke, Hans-Walter Rix, Lester Sandles, Fengwu Sun, Hannah Übler, Christopher N. A. Willmer, Chris Willott, Joris Witstok
TL;DR
This study leverages JWST/JADES deep multi-band imaging to map rest-frame UV-to-NIR sizes of 161 massive quiescent galaxies ($M_*>10^{10}M_⊙$) from $z\sim5$ to $z\sim0.5$, measuring $R_e$ at $\sim0.3$, $0.5$, and $1\,\mu$m. It finds a strong, mass-dependent size evolution with $R_e \propto (1+z)^\beta$ and $\beta \approx -1.25\pm0.20$ across wavelengths, while the rest-frame 1 μm sizes best trace stellar-mass distributions. The UV/optical sizes reveal color gradients, with $R_e^{0.3μm}$ larger by about 45% and $R_e^{0.5μm}$ larger by about 15% relative to $R_e^{1μm}$. The analysis indicates that low-mass quiescent galaxies largely follow the progenitor effect ($R_e \propto (1+z_{form})^{-1}$), whereas high-mass systems show additional growth likely from mergers and ongoing gas accretion, especially at $z>3$ where galaxies are exceptionally compact with $Σ_e \gtrsim 10^{10} M_⊙\,\mathrm{kpc}^{-2}$. The GS-9209 case exemplifies early color gradients and increasing spheroidality, underscoring the rapid establishment of dense central regions in the earliest massive quiescent galaxies. Overall, the work demonstrates JWST’s power to resolve high-redshift galaxy structure and refines our understanding of quenching and structural evolution in the early Universe.
Abstract
We present the UV-to-NIR size evolution of a sample of 161 quiescent galaxies (QGs) with $M_*>10^{10}M_\odot$ over $0.5<z<5$. With deep multi-band NIRCam images in GOODS-South from JADES, we measure the effective radii ($R_e$) of the galaxies at rest-frame 0.3, 0.5 and 1$μm$. On average, QGs are 45% (15%) more compact at rest-frame 1$μm$ than they are at 0.3$μm$ (0.5$μm$). Regardless of wavelengths, the $R_e$ of QGs strongly evolves with redshift, and this evolution depends on stellar mass. For lower-mass QGs with $M_*=10^{10}-10^{10.6}M_\odot$, the evolution follows $R_e\sim(1+z)^{-1.1}$, whereas it becomes steeper, following $R_e\sim(1+z)^{-1.7}$, for higher-mass QGs with $M_*>10^{10.6}M_\odot$. To constrain the physical mechanisms driving the apparent size evolution, we study the relationship between $R_e$ and the formation redshift ($z_{form}$) of QGs. For lower-mass QGs, this relationship is broadly consistent with $R_e\sim(1+z_{form})^{-1}$, in line with the expectation of the progenitor effect. For higher-mass QGs, the relationship between $R_e$ and $z_{form}$ depends on stellar age. Older QGs have a steeper relationship between $R_e$ and $z_{form}$ than that expected from the progenitor effect alone, suggesting that mergers and/or post-quenching continuous gas accretion drive additional size growth in very massive systems. We find that the $z>3$ QGs in our sample are very compact, with mass surface densities $Σ_e\gtrsim10^{10} M_\odot/\rm{kpc}^2$, and their $R_e$ are possibly even smaller than anticipated from the size evolution measured for lower-redshift QGs. Finally, we take a close look at the structure of GS-9209, one of the earliest confirmed massive QGs at $z_{spec}\sim4.7$. From UV to NIR, GS-9209 becomes increasingly compact, and its light profile becomes more spheroidal, showing that the color gradient is already present in this earliest massive QG.