Spitzer Planck Herschel Infrared Cluster (SPHerIC) survey: Candidate
  galaxy clusters at 1.3 < z < 3 selected by high star-formation rate
  There is a lack of large samples of spectroscopically confirmed clusters and
protoclusters at high redshifts, $z>$1.5. Discovering and characterizing
distant (proto-)clusters is important for yielding insights into the formation
of large-scale structure and on the physical processes responsible for
regulating star-formation in galaxies in dense environments. The Spitzer Planck
Herschel Infrared Cluster (SPHerIC) survey was initiated to identify these
characteristically faint and dust-reddened sources during the epoch of their
early assembly. We present Spitzer IRAC observations of 82 galaxy
(proto-)cluster candidates at 1.3<$z_p$<3.0 that were vetted in a two step
process: (1) using Planck to select by color those sources with the highest
star-formation rates, and (2) using Herschel at higher resolution to separate
out the individual red sources. The addition of the Spitzer data enables
efficient detection of the central and massive brightest red cluster galaxies
(BRCGs). We find that BRCGs are associated with highly significant, extended
and crowded regions of IRAC sources which are more overdense than the field.
This result corroborates our hypothesis that BRCGs within the Planck - Herschel
sources trace some of the densest and actively star-forming proto-clusters in
the early Universe. On the basis of a richness-mass proxy relation, we obtain
an estimate of their mean masses which suggests our sample consists of some of
the most massive clusters at z$\approx$2 and are the likely progenitors of the
most massive clusters observed today.
