Chorus II. Subaru/hsc determination of the Lyα luminosity function at Z = 7.0: Constraints on cosmic reionization model parameter

Ryohei Itoh, Masami Ouchi, Haibin Zhang, Akio K. Inoue, Ken Mawatari, Takatoshi Shibuya, Yuichi Harikane, Yoshiaki Ono, Haruka Kusakabe, Kazuhiro Shimasaku, Seiji Fujimoto, Ikuru Iwata, Masaru Kajisawa, Nobunari Kashikawa, Satoshi Kawanomoto, Yutaka Komiyama, Chien Hsiu Lee, Tohru Nagao, Yoshiaki Taniguchi

Research output: Contribution to journalArticlepeer-review


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 & 7. 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. Subject headings: galaxies: formation — galaxies: high-redshift — galaxies: luminosity function — cosmology: observations

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2018 May 15

ASJC Scopus subject areas

  • General

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