Evolution of the Size-Mass Relation of Star-forming Galaxies Since $z=5.5$ Revealed by CEERS

TL;DR

This study uses JWST and HST data to analyze how the size-mass relation of star-forming galaxies has evolved from redshift 5.5 to 0.5, revealing consistent morphology differences and a modest size evolution over cosmic time.

Contribution

It provides new insights into the evolution of the size-mass relation and galaxy morphology at high redshifts using combined JWST and HST imaging data.

Findings

Star-forming and quiescent galaxies have distinct morphologies up to z=5.5.

The size-mass relation slope remains nearly constant with a slight increase at z~4.2.

The size-mass relation's intercept decreases with redshift, with constant scatter.

Abstract

We combine deep imaging data from the CEERS early release JWST survey and HST imaging from CANDELS to examine the size-mass relation of star-forming galaxies and the morphology-quenching relation at stellar masses $\textrm{M}_{\star} \geq 10^{9.5} \ \textrm{M}_{\odot}$ over the redshift range $0.5 < z < 5.5$. In this study with a sample of 2,450 galaxies, we separate star-forming and quiescent galaxies based on their star-formation activity and confirm that star-forming and quiescent galaxies have different morphologies out to $z=5.5$, extending the results of earlier studies out to higher redshifts. We find that star-forming and quiescent galaxies have typical S\'{e}rsic indices of $n\sim1.3$ and $n\sim4.3$, respectively. Focusing on star-forming galaxies, we find that the slope of the size-mass relation is nearly constant with redshift, as was found previously, but shows a modest increase at $z \sim 4.2$. The intercept in the size-mass relation declines out to $z=5.5$ at rates that are similar to what earlier studies found. The intrinsic scatter in the size-mass relation is relatively constant out to $z=5.5$.