SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6–7: Strong Associations of Dusty Star-forming Galaxies

Harikane, Yuichi; Ouchi, Masami; Ono, Yoshiaki; Fujimoto, Seiji; Donevski, Darko; Shibuya, Takatoshi; Faisst, Andreas L.; Goto, Tomotsugu; Hatsukade, Bunyo; Kashikawa, Nobunari; Kohno, Kotaro; Hashimoto, Takuya; Higuchi, Ryo; Inoue, Akio K.; Lin, Yen-Ting; Martin, Crystal L.; Overzier, Roderik; Smail, Ian; Toshikawa, Jun; Umehata, Hideki; Ao, Yiping; Chapman, Scott; Clements, David L.; Im, Myungshin; Jing, Yipeng; Kawaguchi, Toshihiro; Lee, Chien-Hsiu; Lee, Minju M.; Lin, Lihwai; Matsuoka, Yoshiki; Marinello, Murilo; Nagao, Tohru; Onodera, Masato; Toft, Sune; Wang, Wei-Hao

Abstract

We have obtained three-dimensional maps of the universe in ~200 × 200 × 80 comoving Mpc3 (cMpc3) volumes each at z = 5.7 and 6.6 based on a spectroscopic sample of 179 galaxies that achieves gsim80% completeness down to the Lyα luminosity of $\mathrm{log}({L}_{\mathrm{Ly}\alpha }/[\mathrm{erg}\,{{\rm{s}}}^{-1}])=43.0$, based on our Keck and Gemini observations and the literature. The maps reveal filamentary large-scale structures and two remarkable overdensities made out of at least 44 and 12 galaxies at z = 5.692 (z57OD) and z = 6.585 (z66OD), respectively, making z66OD the most distant overdensity spectroscopically confirmed to date, with >10 spectroscopically confirmed galaxies. We compare spatial distributions of submillimeter galaxies at z sime 4–6 with our z = 5.7 galaxies forming the large-scale structures, and detect a 99.97% signal of cross-correlation, indicative of a clear coincidence of dusty star-forming galaxy and dust-unobscured galaxy formation at this early epoch. The galaxies in z57OD and z66OD are actively forming stars with star-formation rates (SFRs) gsim5 times higher than the main sequence, and particularly the SFR density in z57OD is 10 times higher than the cosmic average at the redshift (a.k.a. the Madau-Lilly plot). Comparisons with numerical simulations suggest that z57OD and z66OD are protoclusters that are progenitors of the present-day clusters with halo masses of ~1014 M ⊙.

Citation

Harikane, Y., Ouchi, M., Ono, Y., Fujimoto, S., Donevski, D., Shibuya, T., Faisst, A. L., Goto, T., Hatsukade, B., Kashikawa, N., Kohno, K., Hashimoto, T., Higuchi, R., Inoue, A. K., Lin, Y.-T., Martin, C. L., Overzier, R., Smail, I., Toshikawa, J., Umehata, H., …Wang, W.-H. (2019). SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6–7: Strong Associations of Dusty Star-forming Galaxies. Astrophysical Journal, 883(2), Article 142. https://doi.org/10.3847/1538-4357/ab2cd5

• Journal Article Type: Article
• Acceptance Date: Jun 23, 2019
• Online Publication Date: Sep 30, 2019
• Publication Date: Oct 1, 2019
• Deposit Date: Oct 30, 2019
• Publicly Available Date: Oct 30, 2019
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 883
• Issue: 2
• Article Number: 142
• DOI: https://doi.org/10.3847/1538-4357/ab2cd5
• Public URL: https://durham-repository.worktribe.com/output/1316208