A universal stellar-mass and size relation of galaxies in GOODS-N region

TL;DR

This study reveals a universal relation between stellar mass and galaxy size across a wide redshift range, indicating similar galaxy growth mechanisms over cosmic time regardless of galaxy mass.

Contribution

It establishes a redshift-independent stellar mass-size relation for galaxies, highlighting weak size evolution and suggesting minor mergers influence galaxy growth.

Findings

Size increases by 30-50% for less massive galaxies from z~3 to z~1

Massive galaxies show 70-80% size increase in R_90 from z~3 to z~0.3

Universal relation implies similar stellar mass buildup over cosmic history

Abstract

We present scaling relations between stellar-mass (Mstar) and the size of galaxies at 0.3 < z < 3 for half- (R_50) and 90 percent-light (R_90) radii, using a deep K-band selected catalogue taken with the Subaru Telescope and MOIRCS in the GOODS-North region. The logarithmic slope R \propto Mstar^{0.1-0.2} is independent of redshift in a wide mass range of Mstar ~ 10^8-10^11 Msun, irrespective of galaxy populations (star-forming, quiescent). The offset change is < 50 percent. Provided that optical light in the rest frame traces the stellar mass of galaxies, the universal relation demonstrates that the stellar mass was built up in galaxies over their cosmic histories in a similar manner on average irrelevant to galaxy mass. The small offset in each stellar mass bin from the universal relation shows weak size evolution at a given mass. There is a moderate increase of 30-50 percent for R_50 and R_90 for less massive galaxies (Mstar < 10^10 Msun) from z~3 to z~1, while the sizes remains unchanged or slightly decrease towards z~0.3. For massive galaxies (Mstar > 10^11 Msun), the evolution is ~70-80 % increase in R_90 from z~3 to z~0.3, though that in R_50 is weaker. The evolution of compactness factor, R_50/R_90, which becomes smaller at lower redshift, is suggestive of minor merging effect in the outer envelope of massive galaxies.