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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

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 {log}({L}Lyα }/[{erg} {{{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 ≃ 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 .
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https://hal-insu.archives-ouvertes.fr/insu-03666717
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Submitted on : Thursday, May 12, 2022 - 4:47:00 PM
Last modification on : Saturday, May 14, 2022 - 3:03:48 AM

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yuichi Harikane, Masami Ouchi, yoshiaki Ono, Seiji Fujimoto, Darko Donevski, et al.. 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. The Astrophysical Journal, 2019, 883, ⟨10.3847/1538-4357/ab2cd5⟩. ⟨insu-03666717⟩

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