  Anomalous Narrow-Line Quasars (ANLs) are a population of quasars with narrow
H\beta, and sometimes [O III] broader than ~1000 km/s, in total comprising \sim
10-30% (most likely ~25%) of Type I quasars at 0.2 < z < 0.8. We find that
virial masses using the H\beta and Mg II lines systematically differ for ANLs
by an average of as much as 0.5 dex. Because the broad H\beta component width
increases in ANLs but Mg II does not, we might suspect H\beta-based virial
masses for ANLs are wrong but Mg II masses are correct. If this is due to an
outflow reaching the lower-ionization potential H\beta line, C IV masses will
be similarly flawed. However, we cannot be certain of this explanation without
followup work, and may be unable to identify which quasars are ANLs at z > 0.8.
Therefore, it is essential that ANLs be well-understood and well-modeled in
order to allow the use of virial mass estimators on large optical spectroscopic
catalogs, particularly at z < 0.4 and z > 2.0 where only one broad line is
available for use in mass estimation.

High Energy Astrophysical Phenomena