The evolution of brightest cluster galaxies in the nearby Universe - I. Colours and stellar masses from the Sloan Digital Sky Survey and Wide Infrared Survey Explorer

We present a study of the evolution of brightest cluster galaxies (BCGs) in a sample of clusters at 0.05 ≤ z < 0.35 from the Sloan Digital Sky Survey and Wide Infrared Survey Explorer with halo masses in the range 6 × 10^{13} M_\odot (massive groups)-10^{15.5} M_\odot (Coma-like clusters). We analyse optical and infrared colours and stellar masses of BCGs as a function of the mass of their host haloes. We find that BCGs are mostly red and quiescent galaxies and that a minority (∼9 per cent) of them are star-forming. We find that the optical g - r colours are consistent with those of red sequence galaxies at the same redshifts; however, we detect the presence of a tail of blue and mostly star-forming BCGs preferentially located in low-mass clusters and groups. Although the blue tail is dominated by star-forming galaxies, we find that star-forming BCGs may also have red g - r colours, indicating dust-enshrouded star formation. The fraction of star-forming BCGs increases with redshift and decreases with cluster mass and BCG stellar mass. We find that cool-core clusters host both star-forming and quiescent BCGs; however, non-cool-core clusters are dominated by quiescent BCGs. Star formation appears thus as the result of processes that depend on stellar mass, cluster mass, and cooling state of the intra-cluster medium. Our results suggest no significant stellar mass growth at z < 0.35, supporting the notion that BCGs had accreted most of their mass by z = 0.35. Overall we find a low (1 per cent) active galactic nuclei fraction detected at IR wavelengths.