A Weak Lensing Detection of the Cosmological Distance-Redshift Relation
  Behind Three Massive Clusters
  The amplitude of weak lensing should increase with source distance, rising
steeply behind a lens and saturating at high redshift, providing a
model-independent means of measuring cosmic geometry. We measure the amplitude
of weak lensing with redshift for three massive clusters, A370 (z=0.375),
ZwCl0024+17 (z=0.395) and RXJ1347-11 (z=0.451), using deep, three-colour Subaru
imaging. We define the depth of lensed populations with reference to the COSMOS
and GOODS fields, providing a consistency check of photo-z estimates over a
wide range of redshift and magnitude. The predicted distance-redshift relation
is followed well for the deepest dataset, A370, for a wide range of
cosmologies, and is consistent with less accurate data for the other two
clusters. Scaling this result to a new survey of ~25 massive clusters should
provide a useful cosmological constraint on w, complementing existing
techniques, with distance measurements covering the untested redshift range,
1<z<5.
