(Proposal ID) S17A-132

(PI) Dahle, Hakon

(Proposal Title)
Weak lensing masses of the most massive galaxy clusters at 0.7 < z < 0.9.

(Abstract)
An integral part of the ESA Planck mission has been to conduct an all-sky 
survey for the most massive galaxy clusters in the Universe at redshifts 
up to 1, by measuring the Sunyaev-Zeldovich (SZ) effect. We propose deep 
Hyper Suprime-Cam imaging for weak gravitational lensing measurements of 
the total masses of a new, representative sample of massive, SZ-selected 
clusters at 0.7 < z < 0.9 from {Planck}. Complementary SZ observations will 
be obtained in a guaranteed program at the 30m IRAM telescope, and scheduled 
complementary X-ray observations from {XMM-Newton}. These data will allow us 
to calibrate the relationship between baryonic observables and lensing cluster 
mass at these redshifts. This calibration is absolutely essential for 
cosmological applications of the SZ-selected clusters from Planck. Furthermore,
the proposed observations will for the first time provide lensing-based 
measurements of the radial mass distribution for a representative sample of 
very massive clusters at 0.7 < z < 0.9, selected with minimal bias regarding 
the dynamical state of the clusters. Comparison of these results with 
predictions from theory and simulations will provide an important test of 
the LambdaCDM paradigm. High image quality and large aperture make Subaru 
uniquely suited for this program.