Campus, Varian 355
Galaxy clusters are one of the most powerful cosmological probes because of an exponential tail at the high-mass end of the cluster mass function. The accuracy of mass function measurement is currently limited by systematic uncertainties in cluster mass estimates due to an uncertain physical assumption, e.g., hydrostatic equilibrium when using X-ray observables. On the other hand, weak gravitational lensing can provide unbiased mass estimates because of its direct sensitivity to the dark matter distribution around galaxy clusters. In this talk, I will present the weak lensing mass calibration of galaxy clusters detected by Atacama Cosmology Telescope Polarimeter (ACTPol) through the thermal Sunyaev-Zel'dovich (SZ) effect, using the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) first-year data. The HSC SSP is an ongoing galaxy imaging survey that will cover wide area of the sky (1,400 deg^2) down to the limiting magnitude i~26. The superb image quality, wide field-of-view, and tremendous light-collecting power make HSC one of the best weak lensing instruments in the world. I will first talk about the overview of the HSC survey, especially the high-precision galaxy shape catalog, and then present weak lensing mass measurement of the ACTPol clusters, including detailed studies of systematic uncertainties and comparison of our mass calibration to the previous results in the literature.