Quasar Structure Emerges from the Three Forms of Radiation Pressure
  All quasar spectra show the same atomic features in the optical, UV, near-IR
and soft X-rays over all of cosmic time, luminosity black hole mass and
accretion rate. This is a puzzle. Here I show that it is possible that all of
these atomic features can be accounted for by gas from an accretion disk driven
by the three forms of radiation pressure: electron scattering, line driving and
dust driving. The locations where they successfully drive an escaping wind, and
those where they produce only a failed wind are both needed to produce the
observed features.
