KEK 素粒子原子核研究所・宇宙物理セミナー（関口豊和氏）

概要

The discrepancy in measurements of H0 is the most notable anomaly in contemporary cosmology with significance as large as 6σ. Despite many attempts, there is yet no compelling solution to the H0 tension. In the first part of my talk, I review the H0 tension. In particular, I will clarify why it is so diffcult to solve the tension. In the latter part, I will present our model, which is based on modified recombination in a closed Universe. Starting from general discussion on necessary conditions that successful modified recombination models should satisfy to fit CMB observations, I will demonstrate time-varying me models indeed satisfy those conditions. To fit low-z distance measurements such as baryon acoustic oscillation and type-Ia supernovae, a positive spatial curvature plays an essential role. Compared to the canonical ΛCDM, our model improves the chi-square by more than 23. We also show our model solves the lensing anomaly in the Planck data concurrently.