MOIRCS Deep Survey V: A Universal Relation for Stellar Mass and Surface Brightness of Galaxies

TL;DR

This study reveals a universal linear relation between stellar mass and surface brightness in galaxies across redshifts 0.3 to 3, indicating similar mass assembly processes regardless of galaxy mass.

Contribution

It identifies a redshift-independent slope in the stellar mass–surface brightness relation and demonstrates that galaxy evolution is consistent with pure luminosity evolution up to z~3.

Findings

Universal linear correlation between stellar mass and surface brightness.

Surface brightness evolution follows (1+z)^(-2.0~-0.8).

Galaxy evolution aligns with pure luminosity evolution models.

Abstract

We present a universal linear correlation between the stellar mass and surface brightness (SB) of galaxies at 0.3<z<3, using a deep K-band selected catalog in the GOODS-North region. The correlation has a nearly constant slope, independent of redshift and color of galaxies in the rest-z frame. Considering unresolved compact galaxies, the tight correlation gives a lower boundary of SB for a given stellar mass; lower SB galaxies are prohibited over the boundary. The universal slope suggests that the stellar mass in galaxies was build up over their cosmic histories in a similar manner irrelevant to galaxy mass, as oppose to the scenario that massive galaxies mainly accumulated their stellar mass by major merging. In contrast, SB shows a strong dependence on redshift for a given stellar mass. It evolves as (1+z)^(-2.0~-0.8), in addition to dimming as (1+z)^4 by the cosmological expansion effect. The brightening depends on galaxy color and stellar mass. The blue population (rest-frame U-V<0), which is dominated by young and star-forming galaxies, evolves as ~(1+z)^(-0.8 +-0.3) in the rest-V band. On the other hand, the red population (U-V>0) and the massive galaxies (M_*>10^(10)M_sun) shows stronger brightening, (1+z)^(-1.5+-0.1). Based on the comparison with galaxy evolution models, we find that the phenomena are well explained by the pure luminosity evolution of galaxies out to z~3.