On the cool gaseous haloes of quasars
  We present optical spectroscopy of projected QSO pairs to investigate the
MgII and the CIV absorption features imprinted on the spectrum of the
background object by the gaseous halo surrounding the foreground QSO. We
observed 13 projected pairs in the redshift range 0.7<z<2.2 spanning projected
separations between 60 kpc and 120 kpc. In the spectra of the background QSOs,
we identify MgII intervening absorption systems associated to the foreground
QSOs in 7 out of 10 pairs, and 1 absorption system out of 3 is found for CIV.
The distribution of the equivalent width as a function of the impact parameter
shows that, unlike the case of normal galaxies, some strong absorption systems
(EWr > 1 Ang) are present also beyond a projected radius of ~70 kpc. If we take
into account the mass of the galaxies as an additional parameter that influence
the extent of the gaseous haloes, the distribution of the absorptions connected
to the QSOs is consistent to that of galaxies. In the spectra of the foreground
QSOs we do not detect any MgII absorption lines originated by the gas
surrounding the QSO itself, but in 2 cases these features are present for CIV.
The comparison between the absorption features observed in the transverse
direction and those along the line of sight allows us to comment on the
distribution of the absorbing gas and on the emission properties of the QSOs.
  Based on observations undertaken at the European Southern Observatory (ESO)
Very Large Telescope (VLT) under Programmes 085.B-0210(A) and 086.B-0028(A).
