(Proposal ID) S12B-075

(PI) Takada, Masahiro

(Proposal Title)
Subaru weak lensing observations of ACT SZ-selected galaxy clusters

(Abstract)
We were awarded 1 night for the observation of 2 clusters in S11B, but it was 
canceled due to the telescope trouble. Here, we propose to carry out the 
observation again. The abundance of massive clusters as a function of redshift 
is a very powerful probe of cosmology, when combined with CMB observations.  
The Sunyaev-Zel'dovich (SZ) effect, which is independent of redshift, offers a 
unique means of finding clusters up to high redshifts. However, large-scale SZ 
surveys of cosmological volumes are currently in their infancy, and require 
cross-calibration with weak gravitational lensing (WL) to determine the 
relationship between SZ observables and mass. We request 2 nights in total for 
a multi-band Suprime-Cam observation of 7 clusters that are a complete sample 
of the highest-significance SZ clusters in the redshift range z=0.5--1, found 
from the equatorial region of the Atacama Cosmology Telescope (ACT) survey. 
This observation will allow for a determination of the masses to within 30-40% 
for each cluster, and also for a statistical study of the SZ-WL scaling 
relation in the highest redshift. Our study is part of a multi-wavelength 
study that will enable precision cosmology with SZ-selected cluster samples, 
eventually done in combination with the planned HSC Survey.