The spatial distribution of galaxies within the CMB cold spot in the
  Corona Borealis supercluster
  We study the spatial distribution and colours of galaxies within the region
covered by the cold spot in the cosmic microwave background (CMB) recently
detected by the Very Small Array (VSA; Genova-Santos et al. 2005, 2008) towards
the Corona Borealis supercluster (CrB-SC). The spot is in the northern part of
a region with a radius ~1 degree (~5 Mpc at the redshift of CrB-SC) enclosing
the clusters Abell 2056, 2065, 2059 and 2073, and where the density of
galaxies, excluding the contribution from those clusters, is ~2 times higher
than the mean value in typical intercluster regions of the CrB-SC. Two of such
clusters (Abell 2056 and 2065) are members of the CrB-SC, while the other two
are in the background. This high density intercluster region is quite
inhomogeneous, being the most remarkable feature a large concentration of
galaxies in a narrow filament running from Abell 2065 with a length of ~35
arcmin (~3 Mpc at the redshift of CrB-SC) in the SW-NE direction. This
intercluster population of galaxies probably results from the interaction of
clusters Abell 2065 and 2056. The area subtended by the VSA cold spot shows an
excess of faint (21<r<22) and red (1.1<r-i<1.3) galaxies as compared with
typical values within the CrB-SC intercluster regions. This overdensity of
galaxies shows a radial dependence and extends out to ~15 arcmin. This could be
signature of a previously unnoticed cluster in the background.
