SHELS: Testing Weak Lensing Maps with Redshift Surveys
  Weak lensing surveys are emerging as an important tool for the construction
of "mass selected" clusters of galaxies. We evaluate both the efficiency and
completeness of a weak lensing selection by combining a dense, complete
redshift survey, the Smithsonian Hectospec Lensing Survey (SHELS), with a weak
lensing map from the Deep Lens Survey (DLS). SHELS includes 11,692 redshifts
for galaxies with R < 20.6 in the four square degree DLS field; the survey is a
solid basis for identifying massive clusters of galaxies with redshift z <
0.55. The range of sensitivity of the redshift survey is similar to the range
for the DLS convergence map. Only four the twelve convergence peaks with
signal-to-noise > 3.5 correspond to clusters of galaxies with M > 1.7 x 10^14
solar masses. Four of the eight massive clusters in SHELS are detected in the
weak lensing map yielding a completeness of roughly 50%. We examine the seven
known extended cluster x-ray sources in the DLS field: three can be detected in
the weak lensing map, three should not be detected without boosting from
superposed large-scale structure, and one is mysteriously undetected even
though its optical properties suggest that it should produce a detectable
lensing signal. Taken together, these results underscore the need for more
extensive comparisons among different methods of massive cluster
identification.
