Weak lensing reconstructions in 2D & 3D: implications for cluster
  studies
  We compare the efficiency with which 2D and 3D weak lensing mass mapping
techniques are able to detect clusters of galaxies using two state-of-the-art
mass reconstruction techniques: MRLens in 2D and GLIMPSE in 3D. We simulate
otherwise-empty cluster fields for 96 different virial mass-redshift
combinations spanning the ranges $3\times10^{13}h^{-1}M_\odot \le M_{vir}\le
10^{15}h^{-1}M_\odot$ and $0.05 \le z_{\rm cl} \le 0.75$, and for each generate
1000 realisations of noisy shear data in 2D and 3D. For each field, we then
compute the cluster (false) detection rate as the mean number of cluster
(false) detections per reconstruction over the sample of 1000 reconstructions.
We show that both MRLens and GLIMPSE are effective tools for the detection of
clusters from weak lensing measurements, and provide comparable quality
reconstructions at low redshift. At high redshift, GLIMPSE reconstructions
offer increased sensitivity in the detection of clusters, yielding cluster
detection rates up to a factor of $\sim 10\times$ that seen in 2D
reconstructions using MRLens. We conclude that 3D mass mapping techniques are
more efficient for the detection of clusters of galaxies in weak lensing
surveys than 2D methods, particularly since 3D reconstructions yield unbiased
estimators of both the mass and redshift of the detected clusters directly.
