The Extreme Red Excess in Blazar Ultraviolet Broad Emission Lines
  We present a study of quasars with very redward asymmetric (RA) ultraviolet
(UV) broad emission lines (BELs). An excess of redshifted emission has been
previously shown to occur in the BELs of radio loud quasars and is most extreme
in certain blazars. Paradoxically, blazars are objects that are characterized
by a highly relativistic blue-shifted outflow towards Earth. We show that the
red emitting gas resides in a very broad component (VBC) that is typical of
Population B quasars that are defined by a wide H$\beta$ BEL profile.
Empirically, we find that RA BEL blazars have both low Eddington rates
($\lesssim1\%$) and an inordinately large (order unity) ratio of long term time
averaged jet power to accretion luminosity. The latter circumstance has been
previously shown to be associated with a depressed extreme UV ionizing
continuum. Both properties conspire to produce a low flux of ionizing photons,
two orders of magnitude less than typical Population B quasars. We use CLOUDY
models to demonstrate that a weak ionizing flux is required for gas near the
central black hole to be optimally ionized to radiate BELs with high efficiency
(most quasars over-ionize nearby gas, resulting in low radiative efficiency).
The large gravitational redshift and transverse Doppler shift results in a VBC
that is redshifted by $\sim 2000 -5000$~km~s$^{-1}$ with a correspondingly
large line width. The RA BELs result from an enhanced efficiency (relative to
typical Population B quasars) to produce a luminous, redshifted VBC near the
central black hole.
