The SWIRE-VVDS-CFHTLS surveys: stellar mass assembly over the last 10 Gyears. Evidence for a major build up of the red sequence between z=2 and z=1

TL;DR

This study analyzes stellar mass growth over the past 10 billion years, revealing a significant increase in quiescent galaxies between redshifts 2 and 1, indicating major build-up of the red sequence during this epoch.

Contribution

It provides new insights into the evolution of galaxy populations, especially the rapid growth of the red sequence between z=2 and z=1, based on large multi-survey data analysis.

Findings

Major build-up of the quiescent population between z=2 and z=1.

Stellar mass density of active galaxies remains constant over 8 Gyrs.

Growth in quiescent stellar mass is due to cessation of star formation in active galaxies.

Abstract

(abridged abstract) We present an analysis of the stellar mass growth over the last 10 Gyrs using a large 3.6$\mu$ selected sample. We split our sample into active (blue) and quiescent (red) galaxies. Our measurements of the K-LFs and LD evolution support the idea that a large fraction of galaxies is already assembled at $z\sim 1.2$. Based on the analysis of the evolution of the stellar mass-to-light ratio (in K-band) for the spectroscopic sub-sample, we derive the stellar mass density for the entire sample. We find that the global evolution of the stellar mass density is well reproduced by the star formation rate derived from UV dust corrected measurements. Over the last 8Gyrs, we observe that the stellar mass density of the active population remains approximately constant while it gradually increases for the quiescent population over the same timescale. As a consequence, the growth of the stellar mass in the quiescent population must be due to the shutoff of star formation in active galaxies that migrate into the quiescent population. From $z=2$ to $z=1.2$, we observe a major build-up of the quiescent population with an increase by a factor of 10 in stellar mass, suggesting that we are observing the epoch when an increasing fraction of galaxies are ending their star formation activity and start to build up the red sequence.