Photometric redshifts for galaxies in the Subaru Hyper Suprime-Cam and
  unWISE and a catalogue of identified clusters of galaxies
  We first present a catalogue of photometric redshifts for 14.68 million
galaxies derived from the 7-band photometric data of Hyper Suprime-Cam Subaru
Strategic Program and the Wide-field Infrared Survey Explorer using the
nearest-neighbour algorithm. The redshift uncertainty is about 0.024 for
galaxies of z<0.7, and steadily increases with redshift to about 0.11 at z~2.
From such a large data set, we identify 21,661 clusters of galaxies, among
which 5537 clusters have redshifts z>1 and 642 clusters have z>1.5,
significantly enlarging the high redshift sample of galaxy clusters. Cluster
richness and mass are estimated, and these clusters have an equivalent mass of
M_{500} > 0.7*10^{14} Msun. We find that the stellar mass of the brightest
cluster galaxies (BCGs) in each richness bin does not significantly evolve with
redshift. The fraction of star-forming BCGs increases with redshift, but does
not depend on cluster mass.
