Nagai, Daisuke2016-09-012016-08-302016-09-012016-08-22https://hdl.handle.net/11299/182008In recent years, the kinematic Sunyaev-Zel’dovich (kSZ) effect measurements of galaxy cluster peculiar velocities have emerged as a new promising probe of cosmology and fundamental physics. However, the power of kSZ cosmology is fundamentally limited by an uncertainty the optical depth of galaxy clusters, which depends sensitively on still poorly understood astrophysical processes, such as star formation and feedback from supernovae and active galactic nuclei on the hot X-ray emitting intracluster medium. I will describe the current state of affairs on our understanding of the optical depth of galaxy clusters from both simulations and observations and discuss a roadmap for the use of kSZ effect (and other cluster-based techniques) as a precision cosmological probe in the era of large-scale CMB and galaxy surveys.enICMFTPIPresentation