A Ly{\alpha} blob and zabs {\approx} zem damped Ly{\alpha} absorber in
  the dark matter halo of the binary quasar Q 0151+048
  Q0151+048 is a physical QSO pair at z ~ 1.929 with a separation of 3.3 arcsec
on the sky. In the spectrum of Q0151+048A (qA), a DLA is observed at a higher
redshift. We have previously detected the host galaxies of both QSOs, as well
as a Lya blob. We performed low-resolution spectroscopy with the slit aligned
with the extended emission. We also observed the system using the
medium-resolution VLT/X-shooter spectrograph and the slit aligned with the two
QSOs. We measure systemic redshifts of zem(A)=1.92924{\pm}0.00036 and
zem(B)=1.92863{\pm}0.00042 from the H{\beta} and H{\alpha} emission lines,
respectively. We estimate the masses of the black holes of the two QSOs to be
10^9.33 M{\odot} and 10^8.38 M{\odot} for qA and qB, respectively. From this we
infered the mass of the dark matter halos hosting the two QSOs: 10^13.74
M{\odot} and 10^13.13 M{\odot} for qA and qB, respectively. We observe a
velocity gradient along the major axis of the Lya blob consistent with the
rotation curve of a large disk galaxy, but it may also be caused by gas inflow
or outflow. We detect residual continuum in the DLA trough which we interpret
as emission from the host galaxy of qA. The derived H0 column density of the
DLA is log NH0 = 20.34 {\pm} 0.02. Metal column densities results in an overall
metallicity of 0.01 Z{\odot}. We detect CII* which allows us to make a physical
model of the DLA cloud. From the systemic redshifts of the QSOs, we conclude
that the Lya blob is associated with qA rather than with the DLA. The DLA must
be located in front of both the Lya blob and qA at a distance larger than 30
kpc. The two QSOs accrete at normal eddington ratios. The DM halo of this
double quasar will grow to the mass of our local super-cluster at z=0. We point
out that those objects therefore form an ideal laboratory to study the physical
interactions in a z=2 pre-cursor of our local super-cluster.
