  We present the results of an intermediate resolution (~2 angstrom)
spectroscopy of a sample of 37 candidate Lyman alpha blobs and emitters at
redshift z=3.1 using the DEIMOS spectrograph on the 10 m Keck telescope. The
emission lines are detected for all the 37 objects and have variety in their
line profiles. The Lyman alpha velocity widths (FWHM) of the 28 objects with
higher quality spectra, measured by fitting a single Gaussian profile, are in
the range of 150 - 1700 km/s and correlate with the Lyman alpha spatial
extents. All the 12 Lyman alpha blobs (>16 arcsec^2) have large velocity widths
of > 500 km/s. While there are several possible physical interpretations of the
Lyman alpha velocity widths (motion of gravitationally-bound gas clouds,
inflows, merging of clumps, or outflows from superwinds), the large velocity
widths of the Lyman alpha blobs suggest that they are the sites of massive
galaxy formation. If we assume gravitationally-bound gas clouds, the dynamical
masses of the Lyman alpha blobs are estimated to be ~10^12 - 10^13 Msun. Even
for the case of outflows, the outflow velocities are likely to be the same
order of the rotation velocities as inferred from the observational evidence
for local starburst galaxies.
