The Evolution of the Luminosity Function for Luminous Compact Blue Galaxies to z=1

TL;DR

This study analyzes the evolution of luminous compact blue galaxies (LCBGs) from redshift 0.1 to 1, revealing significant increases in their luminosity and number density, which are key to understanding cosmic star formation history.

Contribution

It provides the largest homogeneous sample of LCBGs to date and derives their luminosity function across four redshift bins, highlighting their evolving role in galaxy populations.

Findings

Characteristic luminosity (M*) increases by ~0.2 mag from z=0.1 to 1.

Number density of LCBGs increases by a factor of four over this redshift range.

LCBGs constitute up to 54% of luminous galaxies at z~0.9.

Abstract

Luminous Compact Blue Galaxies (LCBGs) are compact, star-forming galaxies that are rarely observed in the local universe but abundant at z=1. This increase in LCBG number density over cosmic lookback time roughly follows the increase in the star formation rate density of the universe over the same period. We use publicly available data in the COSMOS field to study the evolution of the largest homogeneous sample of LCBGs to date by deriving their luminosity function in four redshift bins over the range $0.1\leq~z\leq1$. We find that over this redshift range, the characteristic luminosity (M$^{*}$) increases by $\sim$0.2 mag, and the number density increases by a factor of four. While LCBGs make up only about $18\%$ of galaxies more luminous than M$_{B}=-$18.5 at $z\sim0.2$, they constitute roughly $54\%$ at z$\sim$0.9. The strong evolution in number density indicates that LCBGs are an important population of galaxies to study in order to better understand the decrease in the star formation rate density of the universe since $z\sim1$.