2010ApJ...723..869O

We present the Lyα luminosity function (LF), clustering measurements, and Lyα line profiles based on the largest sample to date of 207 Lyα emitters (LAEs) at z = 6.6 on the 1 deg² sky of Subaru/XMM-Newton Deep Survey field. Our z = 6.6 Lyα LF including cosmic variance estimates yields the best-fit Schechter parameters of φ* = 8.5^+3.0_–2.2x10^–4/Mpc3 and L*_Lyα= 4.4^+0.6_–0.6x10⁴² erg/s with a fixed α = -1.5, and indicates a decrease from z = 5.7 at the ><90% confidence level. However, this decrease is not large, only ≃30% in Lyα luminosity, which is too small to have been identified in the previous studies. A clustering signal of z = 6.6 LAEs is detected for the first time. We obtain the correlation length of r₀= 2-5 h^–1₁₀₀ Mpc and a bias of b= 3-6, and find no significant boost of clustering amplitude by reionization at z = 6.6. The average hosting dark halo mass inferred from clustering is 10¹⁰-10¹¹ M_☉, and a duty cycle of LAE population is roughly ∼1%, albeit with large uncertainties. The average of our high-quality Keck/DEIMOS spectra shows an FWHM velocity width of 251±16 km/s. We find no large evolution of the Lyα line profile from z = 5.7 to 6.6, and no anti-correlation between Lyα luminosity and line width at z = 6.6. The combination of various reionization models and our observational results about the LF, clustering, and line profile indicates that there would exist a small decrease of the intergalactic medium's (IGM's) Lyα transmission owing to reionization, but that the hydrogen IGM is not highly neutral at z = 6.6. Our neutral-hydrogen fraction constraint implies that the major reionization process took place at z >< 7.