The role of AGN activity in the building up of the BCG at z~1.6
  XDCPJ0044.0-2033 is one of the most massive galaxy cluster at z~1.6, for
which a wealth of multi-wavelength photometric and spectroscopic data have been
collected during the last years. I have reported on the properties of the
galaxy members in the very central region (~70kpc x 70kpc) of the cluster,
derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy,
together with Chandra X-ray, ALMA and JVLA radio data. In the core of the
cluster, we have identified two groups of galaxies (Complex A and Complex B),
seven of them confirmed to be cluster members, with signatures of ongoing
merging. These galaxies show perturbed morphologies and, three of them show
signs of AGN activity. In particular, two of them, located at the center of
each complex, have been found to host luminous, obscured and highly accreting
AGN (lambda=0.4-0.6) exhibiting broad Halpha line. Moreover, a third optically
obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The
AGN at the center of Complex B is detected in X-ray while the other two, and
their companions, are spatially related to radio emission. The three AGN
provide one of the closest AGN triple at z>1 revealed so far with a minimum
(maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN
activity in a highly star-forming region associated to the crowded core of a
galaxy cluster at z~1.6, suggests that these processes have a key role in
shaping the nascent Brightest Cluster Galaxy, observed at the center of local
clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033
could form a BCG of Mstar ~ 10^{12} Msun hosting a BH of 2 x 10^{8}-10^{9}Msun,
in a time scale of the order of 2.5 Gyrs.
