The Colors of Central and Satellite Galaxies in zCOSMOS out to z ~ 0.8 and Implications for Quenching

TL;DR

This study investigates the color and quenching of central and satellite galaxies up to redshift 0.8, revealing that satellite galaxies are more likely to be quenched than centrals, with similar efficiencies to local universe observations.

Contribution

It extends the analysis of galaxy quenching and satellite effects to higher redshifts, demonstrating the consistency of environmental quenching over cosmic time.

Findings

Satellite galaxies have higher quenched fractions than centrals at all redshifts.

Satellite quenching efficiency is approximately 0.5, independent of stellar mass.

Mass functions of blue and red galaxies align with SDSS-based models.

Abstract

We examine the red fraction of central and satellite galaxies in the large zCOSMOS group catalog out to z ~ 0.8 correcting for both the incompleteness in stellar mass and for the less than perfect purities of the central and satellite samples. We show that, at all masses and at all redshifts, the fraction of satellite galaxies that have been quenched, i.e., are red, is systematically higher than that of centrals, as seen locally in the Sloan Digital Sky Survey (SDSS). The satellite quenching efficiency, which is the probability that a satellite is quenched because it is a satellite rather than a central, is, as locally, independent of stellar mass. Furthermore, the average value is about 0.5, which is also very similar to that seen in the SDSS. We also construct the mass functions of blue and red centrals and satellites and show that these broadly follow the predictions of the Peng et al. analysis of the SDSS groups. Together, these results indicate that the effect of the group environment in quenching satellite galaxies was very similar when the universe was about a half its present age, as it is today.