Size - Stellar Mass Relation and Morphology of Quiescent Galaxies at $z\ge 3$ in Public $JWST$ Fields

Abstract

We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at $z\ge 3$ 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 $2.8<z_{\mathrm{phot}}<4.6$ with publicly available $JWST$ data. Their sizes are constrained by fitting the Sérsic profile to all available NIRCam images. We see a negative correlation between the observed wavelength and the size in our sample and derive their size at the rest-frame $0.5\mu \mathrm{m}$ taking into account this trend. Our quiescent galaxies show a significant correlation between the rest-frame $0.5\mu \mathrm{m}$ size and the stellar mass at $z\ge 3$. The analytical fit for them at $\log (M_{\star }/M_{\odot })>10.3$ implies that our size - stellar mass relations are below those at lower redshifts, with the amplitude of $\sim 0.6\mathrm{kpc}$ 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 $z\sim 3-5$. Our sample is mainly composed of galaxies with bulge-like structures according to their median Sérsic index and axis ratio of $n\sim 3-4$ and $q\sim 0.6-0.8$, respectively. On the other hand, there is a trend of increasing fraction of galaxies with low Sérsic index, suggesting $3<z<5$ might be the epoch of onset of morphological transformation with a fraction of very notable disky quenched galaxies.

25 pages, 17 figures, 3 tables; accepted for publication in ApJ

Cited by in corpus (2)

• EPOCHS VI: The Size and Shape Evolution of Galaxies since z ~ 8 with JWST Observations
• JWST/NIRSpec spectroscopy of intermediate-mass quiescent galaxies at $z\sim 3-4$