Evolution of the cluster optical galaxy luminosity function in the CFHTLS: breaking the degeneracy between mass and redshift

Abstract

Obtaining large samples of galaxy clusters is important for cosmology: cluster counts as a function of redshift and mass can constrain the parameters of our Universe. They are also useful in order to understand the formation and evolution of clusters. We develop an improved version of the Adami & MAzure Cluster FInder (AMACFI), now the Adami, MAzure & Sarron Cluster FInder (AMASCFI), and apply it to the 154 deg 2 of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) to obtain a large catalogue of 1371 cluster candidates with mass M 200 > 10 14 M and redshift z ≤ 0.7. We derive the selection function of the algorithm from the Millennium simulation, and cluster masses from a richness-mass scaling relation built from matching our candidates with X-ray detections. We study the evolution of these clusters with mass and redshift by computing the i -band galaxy luminosity functions (GLFs) for the early-type (ETGs) and late-type galaxies (LTGs). This sample is 90% pure and 70% complete, and therefore our results are representative of a large fraction of the cluster population in these redshift and mass ranges. We find an increase in both the ETG and LTG faint populations with decreasing redshift (with Schechter slopes α ETG = −0.65 ± 0.03 and α LTG = −0.95 ± 0.04 at z = 0.6, and α ETG = −0.79 ± 0.02 and α LTG = −1.26 ± 0.03 at z = 0.2) and also a decrease in the LTG (but not the ETG) bright end. Our large sample allows us to break the degeneracy between mass and redshift, finding that the redshift evolution is more pronounced in high-mass clusters, but that there is no significant dependence of the faint end on mass for a given redshift. These results show that the cluster red sequence is mainly formed at redshift z > 0.7, and that faint ETGs continue to enrich the red sequence through quenching of brighter LTGs at z ≤ 0.7. The efficiency of this quenching is higher in large-mass clusters, while the accretion rate of faint LTGs is lower as the more massive clusters have already emptied most of their environment at higher redshifts.

The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey – II. X-ray and optical properties of the cluster sample

“…We can see that the faint end slope is flatter at high redshift in the r and z bands, but not in the i band, so it is difficult to reach any definite conclusion. A small trend of a flattening faint end slope was also found by Sarron et al (2018), as seen in their Fig. 12, but here also the trend is stronger for blue galaxies, and since we are only studying the GLFs of red galaxies here, we cannot draw firm conclusions on the variation of GLF parameters with redshift.…”

“…The absence of a variation of the GLF with cluster mass was already noted in the extensive study of cluster GLFs made by Sarron et al (2018), based on a catalogue of 1371 cluster candidates in the Canada France Hawaii Telescope Legacy Survey (see their Fig. B.2).…”

“…These authors found that it is only when blue and red galaxies are separated that the GLFs of blue and red galaxies start showing differences with cluster mass. Here, we are only studying red galaxies, but our cluster sample is much smaller than that of Sarron et al (2018), so we cannot reach a definite conclusion on the variation of Schechter fit parameters with cluster mass.…”

Pre-processing of galaxies in cosmic filaments around AMASCFI clusters in the CFHTLS

“…3.2.1. We investigated the scaling between the connectivity and cluster mass in the CFHTLS-W1 field from AMASCFI clusters using three mass bins 14 Sarron et al (2018).…”

“…In this paper we focus on the study of filaments in the infall regions of clusters in the CFHTLS survey up to z = 0.7 based on the AMASCFI cluster catalogue from Sarron et al (2018) and on the detection of filaments based on photometric redshifts with a method adapted from Laigle et al (2018). In Sect.…”