Survey of Extremely High-velocity Outflows in Sloan Digital Sky Survey
  Quasars
  We present a survey of extremely high-velocity outflows (EHVOs) in quasars,
defined by speeds between 0.1c and 0.2c. This region of the parameter space has
not been included in previous surveys, but it might present the biggest
challenge for theoretical models and it might be a large contributor to
feedback due to the outflows' potentially large kinetic power. Using the Sloan
Digital Sky Survey, we find 40 quasar spectra with broad EHVO CIV absorption,
10 times more than the number of previously known cases. We characterize the
EHVO absorption and find that in 26 cases, CIV is accompanied by NV and/or OVI
absorption. We find that EHVO quasars lack HeII emission and have overall
larger bolometric luminosities and black hole masses than those of their parent
sample and BALQSOs, while we do not find significant differences in their
Eddington ratios. We also report a trend toward larger black hole masses as the
velocity of the outflowing gas increases in the BALQSOs in our sample. The
overall larger Lbol and lack of HeII emission of EHVO quasars suggest that
radiation is likely driving these outflows. We find a potential evolutionary
effect as EHVO quasars seem to be more predominant at large redshifts. We
estimate that the kinetic power of these outflows may be similar to or even
larger than that of the outflows from BALQSOs as the velocity factor increases
this parameter by 1-2.5 orders of magnitude. Further study of EHVO quasars will
help improve our understanding of quasar physics.
