The Halo from the Outside In: QSO Absorption Lines
  Studies of high resolution quasar absorption lines (QALs), arising from gas in local and z < 1.5 galaxies, provide direct probes of the kinematic, chemical, and ionization conditions and evolution of Milky Way-like galaxies. Inferences drawn from these studies provide a powerful analog for those based upon direct studies of the Halo. The observed gas kinematics and velocity evolution reveal that galactic halos are complex dynamical components, consistent with Searle--Zinn formation scenarios. 
Christopher W. Churchill and Steven S. Vogt (University of California,   Santa Cruz)