Environment or Outflows? New insight into the origin of narrow
  associated QSO absorbers
  Recent detailed studies of Narrow Absorption Line (NAL) systems in
QSO-spectra have revealed that at least 50% of QSOs have NALs associated with
the central engine, and in most cases they are found to be outflowing. Will
studies of NALs provide the much sort after evidence for ubiquitous QSO
feedback that can halt the formation of stars in galaxies? I present new
results on the distribution of line-of-sight velocity offsets between MgII
absorbers and their background QSOs, based on a large catalogue of absorbers
from SDSS DR6 and greatly improved QSO-redshift estimates. My analysis reveals
a high-velocity population of MgII NALs extending out to at least 6000 km/s
from the QSOs, which cannot be ascribed to the clustering of local galaxies,
similar to that observed recently for CIV absorbers. The very existence of such
low ionisation gas clouds in the intense ionising field of the QSO suggests
that we may indeed be witnessing the mechanical expulsion of gas, alongside the
heating previously observed. I also show that there is a significant excess of
low-velocity MgII NALs in radio-loud QSOs compared to radio-quiet QSOs. In the
near future, improved QSO clustering results will allow us to say whether this
is due to environmental or feedback effects.
