Estimating dark matter mass for the most massive high-z galaxy cluster, SPT-CL J2106-5844 using weak-lensing analysis with HST observations

SPT-CL J2106-5844 is known to be one of the most massive galaxy clusters ($M_{200}{\sim}1.27{\times}10^{15}M_{sun}$) ever found at z > 1. Given its redshift (z ~ 1.132), the mass of this cluster estimated by Sunyaev-Zel'dovich effect and X-ray observation is too large compared with the current ${\Lambda}CDM$ cosmology prediction. Mass estimation from these methods can be biased because they require assumptions on hydrostatic equilibrium, which are not guaranteed to hold at such high redshift (about 40% of the current age of the Universe). Thus, we need to verify the mass of this interesting cluster using gravitational lensing, which does not require such assumptions. In this work, we present our preliminary result of dark matter mass and its spatial mass distribution of SPT-CL J2106-5844 using weak-lensing analysis based on HST optical/NIR deep imaging data. We compare mass estimates from different sources and discuss cosmological implications.