A Successful Broad-band Survey for Giant Lya Nebulae II: Spectroscopic
  Confirmation
  Using a systematic broad-band search technique, we have carried out a survey
for large Lya nebulae (or Lya "blobs") at 2<z<3 within 8.5 square degrees of
the NOAO Deep Wide-Field Survey (NDWFS) Bootes field, corresponding to a total
survey comoving volume of ~10^8 h_70^-3 Mpc^3. Here, we present our
spectroscopic observations of candidate giant Lya nebulae. Of 26 candidates
targeted, 5 were confirmed to have Lya emission at 1.7<z<2.7, four of which
were new discoveries. The confirmed Lya nebulae span a range of Lya equivalent
widths, colors, sizes, and line ratios, and most show spatially-extended
continuum emission. The remaining candidates did not reveal any strong emission
lines, but instead exhibit featureless, diffuse, blue continuum spectra. Their
nature remains mysterious, but we speculate that some of these might be Lya
nebulae lying within the redshift desert (i.e., 1.2<z<1.6). Our spectroscopic
follow-up confirms the power of using deep broad-band imaging to search for the
bright end of the Lya nebula population across enormous comoving volumes.
