학술논문
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
Document Type
article
Author
Harikane, Y; Ouchi, M; Ono, Y; Fujimoto, S; Donevski, D; Shibuya, T; Faisst, AL; Goto, T; Hatsukade, B; Kashikawa, N; Kohno, K; Hashimoto, T; Higuchi, R; Inoue, AK; Lin, YT; Martin, CL; Overzier, R; Smail, I; Toshikawa, J; Umehata, H; Ao, Y; Chapman, S; Clements, DL; Im, M; Jing, Y; Kawaguchi, T; Lee, CH; Lee, MM; Lin, L; Matsuoka, Y; Marinello, M; Nagao, T; Onodera, M; Toft, S; Wang, WH
Source
Astrophysical Journal. 883(2)
Subject
Language
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 ⪆80% completeness down to the Lyα luminosity of, 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 ≃ 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) ⪆5 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 o˙