Towards modelling Ghostly DLAs
  We use simple models of the spatial structure of the quasar broad line region
(BLR) to investigate the properties of so-called ghostly damped Lyman-{\alpha}
(DLA) systems detected in SDSS data. These absorbers are characterized by the
presence of strong metal lines but no Hi Lyman-{\alpha} trough is seen in the
quasar spectrum indicating that, although the region emitting the quasar
continuum is covered by an absorbing cloud, the BLR is only partially covered.
One of the models has a spherical geometry, another one is the combination of
two wind flows whereas the third model is a Keplerian disk. The models can
reproduce the typical shape of the quasar Lyman-{\alpha} emission and different
ghostly configurations. We show that the DLA Hi column density can be recovered
precisely independently of the BLR model used. The size of the absorbing cloud
and its distance to the centre of the AGN are correlated. However it may be
possible to disentangle the two using an independent estimate of the radius
from the determination of the particle density. Comparison of the model outputs
with SDSS data shows that the wind and disk models are more versatile than the
spherical one and can be more easily adapted to the observations. For all the
systems we derive logN(Hi)(cm^{-2})>20.5. With higher quality data it may be
possible to distinguish between the models.
