Morphological Demographics of Galaxies at z ∼ 10–16: Log-normal Size Distribution and Exponential Profiles Consistent with the Disk Formation Scenario

We homogeneously investigate the morphological properties of 169 galaxies at z  ∼ 10–16 with deep JWST NIRCam images employing our established techniques of GALFIT modeling and uncertainty evaluation (systematics+statistics). We obtain effective radii r _e ranging 20–500 pc, with a distribution significantly broader than the scatter made by the uncertainties. We find that the r _e distribution is well described by a log-normal distribution with a mean of ${r}_{{{\rm{e}}}}=13{3}_{-12}^{+13}$ pc and a standard deviation of ${\sigma }_{{\mathrm{ln}}\,{r}_{{{\rm{e}}}}}=0.52\pm 0.08$ . The standard deviation is comparable to that of local galaxies, indicating no significant evolution over z  ∼ 0–10. We also find that the axis ratio distribution is nearly uniform, statistically similar to that of local spirals. We estimate the virial radius r _vir from the stellar masses via the star formation main sequence and stellar-to-halo mass relation, obtaining a stellar-to-halo size ratio ${r}_{{{\rm{e}}}}/{r}_{{\mathrm{vir}}}=0.01{5}_{-0.005}^{+0.015}$ , which is comparable to those of star-forming galaxies in the local and low- z Universe. Our results of (1) the log-normal r _e distribution, (2) the uniform axis ratio distribution, and (3) a mean radial profile consistent with an exponential profile ( n  = 1.3 ± 0.6) suggest that galaxies at z  ∼ 10–16 generally follow the classical galaxy disk formation scenario with a specific disk angular momentum fraction of j _d / m _d  ∼ 0.5–1. Interestingly, we identify two remarkable outliers GN-z11 ( z _spec  = 10.60) and GHZ2 ( z _spec  = 12.34) with ${r}_{{{\rm{e}}}}=5{5}_{-6}^{+5}$ pc and 39 ± 11 pc, respectively, that may not be explained by disk structures but by active galactic nucleus or compact star-forming galaxies merging underway in short periods of time, as reproduced in numerical simulations.