A census of stellar mass in ten massive haloes at z ∼ 1 from the GCLASS Survey

Aims. We study the stellar mass content of massive haloes in the redshift range 0.86 < z < 1.34, by measuring (1) the stellar mass in the central galaxy versus total dynamical halo mass; (2) the total stellar mass (including satellites) versus total halo mass; and (3) the radial stellar mass and number density profiles for the ensemble halo. Methods. We use a Ks-band selected catalogue for the 10 clusters in the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS), with photometric redshifts and stellar masses measured from 11-band SED fitting. Combining the photometric catalogues with the deep spectroscopic component of GCLASS, we correct the cluster galaxy sample for interlopers. We also perform a dynamical analysis of the cluster galaxies to estimate the halo mass M200 for each cluster based on a measurement of its velocity dispersion. Results. (1) We find that the central galaxy stellar mass fraction decreases with total halo mass and that this is in reasonable, quantitative agreement with measurements from abundance matching studies at z ∼ 1. (2) The total stellar mass fractions of these systems decrease with halo mass, indicating that lower mass systems are more efficient at transforming baryons into stars. We find the total stellar mass to be a good proxy for total halo mass, with a small intrinsic scatter. When we compare these results from GCLASS with literature measurements, we find that the stellar mass fraction at fixed halo mass shows no significant evolution in the range 0 < z < 1. (3) We measure a relatively high NFW concentration parameter cg ∼ 7 for the stellar mass distribution in these clusters, and debate a possible scenario for explaining the evolution of the stellar mass distribution from the GCLASS sample to their likely descendants at lower redshift. Conclusions. The stellar mass measurements in the z ∼ 1 haloes provided by GCLASS puts constraints on the stellar mass assembly history of clusters observed in the local Universe. A simple model shows that the stellar mass content of GCLASS can evolve in typical distributions observed at lower redshifts if the clusters primarily accrete stellar mass onto the outskirts.