Reverberation Mapping of Luminous Quasars at High-z
  We present Reverberation Mapping (RM) results for 17 high-redshift,
high-luminosity quasars with good quality R-band and emission line light
curves. We are able to measure statistically significant lags for Ly_alpha (11
objects), SiIV (5 objects), CIV (11 objects), and CIII] (2 objects). Using our
results and previous lag determinations taken from the literature, we present
an updated CIV radius--luminosity relation and provide for the first time
radius--luminosity relations for Ly_alpha, SiIV and CIII]. While in all cases
the slope of the correlations are statistically significant, the zero points
are poorly constrained because of the lack of data at the low luminosity end.
We find that the emissivity weighted distance from the central source of the
Ly_alpha, SiIV and CIII] line emitting regions are all similar, which
corresponds to about half that of the H_beta region. We also find that 3/17 of
our sources show an unexpected behavior in some emission lines, two in the
Ly_alpha light curve and one in the SiIV light curve, in that they do not seem
to follow the variability of the UV continuum. Finally, we compute RM black
hole masses for those quasars with highly significant lag measurements and
compare them with CIV single--epoch (SE) mass determinations. We find that the
RM-based black hole mass determinations seem smaller than those found using SE
calibrations.
