Abstract
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+3.0−2.2 × 10−4 Mpc−3 and L*Lyα = 4.4+0.6−0.6 × 1042 erg s−1 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−1. 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.
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