2025ApJS..277...37U

We present luminosity functions (LFs) and angular correlation functions (ACFs) derived from 18,960 Lyα emitters (LAEs) at z = 2.2-7.3 over a wide survey area of ≲24 deg² that are identified in the narrowband data of the HSC-SSP and CHORUS surveys. Confirming the large sample with 241 spectroscopically identified LAEs, we determine Lyα LFs and ACFs in the brighter luminosity range down to 0.5L_⋆, and confirm that our measurements are consistent with previous studies but offer significantly reduced statistical uncertainties. The improved precision of our ACFs allows us to clearly detect one-halo terms at some redshifts, and provides large-scale bias measurements that indicate host halo masses of ∼10¹¹M_⊙ over z ≃ 2-7. By comparing our Lyα LF (ACF) measurements with reionization models, we estimate the neutral hydrogen fractions in the intergalactic medium to be x_H i_ < 0.05 (= ${0.06}_{-0.03}^{+0.12}$) at z = 5.7 and x_H i_ = $0.1{5}_{-0.08}^{+0.10}$ (${0.21}_{-0.14}^{+0.19}$), $0.1{8}_{-0.12}^{+0.14}$, and $0.7{5}_{-0.13}^{+0.09}$ at z = 6.6, 7.0, and 7.3, respectively. Our findings suggest that the neutral hydrogen fraction remains relatively low, x_H I ≲ 0.2, at z = 5-7, but increases sharply at z > 7, reaching x_H i_ ∼ 0.9 by z ≃ 8-9, as indicated by recent JWST studies. The combination of our results from LAE observations with recent JWST observations suggests that the major epoch of reionization occurred at z ∼ 7-8, likely driven by the emergence of massive sources emitting significant ionizing photons.