The environmental dependence of the stellar mass function at z ~ 1: Comparing cluster and field between the GCLASS and UltraVISTA surveys

Aims. We present the stellar mass functions (SMFs) of star-forming and quiescent galaxies from observations of ten rich, red-sequence selected, clusters in the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS) in the redshift range 0.86 < z < 1.34. We compare our results with field measurements at similar redshifts using data from a K_s-band selected catalogue of the COSMOS/UltraVISTA field. Methods. We construct a K _s-band selected multi-colour catalogue for the clusters in eleven photometric bands covering u-8 μm, and estimate photometric redshifts and stellar masses using spectral energy distribution fitting techniques. To correct for interlopers in our cluster sample, we use the deep spectroscopic component of GCLASS, which contains spectra for 1282 identified cluster and field galaxies taken with Gemini/GMOS. This allowed us to correct cluster number counts from a photometric selection for false positive and false negative identifications. Both the photometric and spectroscopic samples are sufficiently deep that we can probe the SMF down to masses of 10¹⁰ M. Results. We distinguish between star-forming and quiescent galaxies using the rest-frame U - V versus V - J diagram, and find that the best-fitting Schechter parameters α and Mare similar within the uncertainties for these galaxy types within the different environments. However, there is a significant difference in the shape and normalisation of the total SMF between the clusters and the field sample. This difference in the total SMF is primarily a reflection of the increased fraction of quiescent galaxies in high-density environments. We apply a simple quenching model that includes components of mass- and environment-driven quenching, and find that in this picture 45_-3⁺⁴% of the star-forming galaxies, which normally would be forming stars in the field, are quenched by the cluster. Conclusions. If galaxies in clusters and the field quench their star formation via different mechanisms, these processes have to conspire in such a way that the shapes of the quiescent and star-forming SMF remain similar in these different environments.