2018/05/31 by Ryohei Itoh, Masami Ouchi, Haibin Zhang +16
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aadfe4
13 pages, 15 figures, accepted in ApJ
arxiv created 2018/09/18 · arxiv updated 2018/11/07
We present the Lyα luminosity function (LF) derived from 34 Lyα emitters (LAEs) at z=7.0 on the sky of 3.1 deg2, the largest sample compared to those in the literature obtained at a redshift z\gtrsim7. The LAE sample is made by deep large-area Subaru narrowband observations conducted by the Cosmic HydrOgen Reionization Unveiled with Subaru (CHORUS) project. The z=7.0 Lyα LF of our project is consistent with those of the previous DECam and Subaru studies at the bright and faint ends, respectively, while our z=7.0 Lyα LF has uncertainties significantly smaller than those of the previous study results. Exploiting the small errors of our measurements, we investigate the shape of the faint to bright-end Lyα LF. We find that the z=7.0 Lyα LF shape can be explained by the steep slope of α≃ -2.5 suggested at z=6.6, and that there is no clear signature of a bright-end excess at z≃ 7 claimed by the previous work, which was thought to be made by the ionized bubbles around bright LAEs whose Lyα photons could easily escape from the partly neutral IGM at z ≃ 7. We estimate the Lyα luminosity densities (LDs) with Lyα LFs at z≃ 6-8 given by our and the previous studies, and compare the evolution of the UV-continuum LD estimated with dropouts. The Lyα LD monotonically decreases from z∼ 6 to 8, and evolves stronger than the UV-continuum LD, indicative of the Lyα damping wing absorption of the IGM towards the heart of the reionization epoch.