Silverrush. VII. Subaru/HSC identifications of 42 protocluster candidates AT z - 6 − 7 with the spectroscopic redshifts up to z = 6.574: Implications for cosmic reionization

Ryo Higuchi, Masami Ouchi, Yoshiaki Ono, Takatoshi Shibuya, Jun Toshikawa, Yuichi Harikane, Takashi Kojima, Yi Kuan Chiang, Eiichi Egami, Nobunari Kashikawa, Roderik Overzier, Akira Konno, Akio K. Inoue, Kenji Hasegawa, Seiji Fujimoto, Tomotsugu Goto, Shogo Ishikawa, Kei Ito, Yutaka Komiyama, Masayuki Tanaka

Research output: Contribution to journalArticlepeer-review

Abstract

We report fourteen and twenty-eight protocluster candidates at z = 5.7 and 6.6 over 14 and 19 deg2 areas, respectively, selected from 2,230 (259) Lyα emitters (LAEs) photometrically (spectroscopically) identified with Subaru/Hyper Suprime-Cam (HSC) deep images (Keck, Subaru, and Magellan spectra and the literature data). Six out of the 42 protocluster candidates include 1 − 12 spectroscopically confirmed LAEs at redshifts up to z = 6.574. By the comparisons with the cosmological Lyα radiative transfer (RT) model reproducing LAEs with the reionization effects, we find that more than a half of these protocluster candidates are progenitors of the present-day clusters with a mass of & 1014M. We then investigate the correlation between LAE overdensity δ and Lyα rest-frame equivalent width EWLyrestα, because the cosmological Lyα RT model suggests that a slope of EWLyrestα-δ relation is steepened towards the epoch of cosmic reionization (EoR), due to the existence of the ionized bubbles around galaxy overdensities easing the escape of Lyα emission from the partly neutral intergalactic medium (IGM). The available HSC data suggest that the slope of the EWLyrestα-δ correlation does not evolve from the post-reionization epoch z = 5.7 to the EoR z = 6.6 beyond the moderately large statistical errors. There is a possibility that we would detect the evolution of the EWLyrestα - δ relation from z = 5.7 to 7.3 by the upcoming HSC observations providing large samples of LAEs at z = 6.6 − 7.3.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2018 Jan 1

Keywords

  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift

ASJC Scopus subject areas

  • General

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