The Sloan Digital Sky Survey Reverberation Mapping Project: First
  Broad-line Hbeta and MgII Lags at z>~0.3 from six-Month Spectroscopy
  Reverberation mapping (RM) measurements of broad-line region (BLR) lags in
z>0.3 quasars are important for directly measuring black hole masses in these
distant objects, but so far there have been limited attempts and success given
the practical difficulties of RM in this regime. Here we report preliminary
results of 15 BLR lag measurements from the Sloan Digital Sky Survey
Reverberation Mapping (SDSS-RM) project, a dedicated RM program with
multi-object spectroscopy designed for RM over a wide redshift range. The lags
are based on the 2014 spectroscopic light curves alone (32 epochs over 6
months) and focus on the Hbeta and MgII broad lines in the 100 lowest-redshift
(z<0.8) quasars included in SDSS-RM; they represent a small subset of the lags
that SDSS-RM (including 849 quasars to z~4.5) is expected to deliver. The
reported preliminary lag measurements are for intermediate-luminosity quasars
at 0.3<~z<0.8, including 9 Hbeta lags and 6 MgII lags, for the first time
extending RM results to this redshift-luminosity regime and providing direct
quasar black hole mass estimates over ~ half of cosmic time. The MgII lags also
increase the number of known MgII lags by several-fold, and start to explore
the utility of MgII for RM at high redshift. The location of these new lags at
higher redshifts on the observed BLR size-luminosity relationship is
statistically consistent with previous Hbeta results at z<0.3. However, an
independent constraint on the relationship slope at z>0.3 is not yet possible
due to the limitations in our current sample. Our results demonstrate the
general feasibility and potential of multi-object RM for z>0.3 quasars.
