ELPIS: Accelerated metal and dust enrichment in a proto-cluster core at $z\approx8$

Hideki Umehata; Yoichi Tamura; Yoshinobu Fudamoto; Yurina Nakazato; Daniel Ceverino; Naoki Yoshida; Akio K. Inoue; Ryota Ikeda; Yuma Sugahara; Shutaro Inui; Santiago Arribas; Tom Bakx; Masato Hagimoto; Takuya Hashimoto; Luis Colina; Yi W. Ren; Wataru Osone; Alejandro Crespo Gomez; Ken Mawatari; Javier Alvarez-Marquez

arXiv · 2510.11788

ELPIS: Accelerated metal and dust enrichment in a proto-cluster core at $z\approx8$

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Abstract

We present a study of the metal, dust, and molecular gas content in galaxies within the A2744-z7p9OD proto-cluster at z ~ 7.88. We focus on two galaxy groups, the Quintet and the Chain, which are covered by the ELPIS survey (The Emission-Line Protocluster Imaging Survey of the furthest overdensity beyond Pandora's Cluster Abell 2744). [C II] 158 um emission is detected in five galaxies, revealing molecular gas reservoirs with log(M_gas/Msun) ~ 9.0-9.6, while dust continuum at the observed frame of 1.26 mm is detected in three galaxies, yielding dust masses of log(M_dust/Msun) ~ 6.0-6.4, assuming a dust temperature of T_dust = 45 (+15, -15) K. The derived properties, including stellar-to-dust mass ratios of log(M_dust/M_star) ~ -3 to -2 at log(M_star/Msun) ~ 9, and dust-to-gas mass ratios of log(M_dust/M_gas) ~ -4 to -3 at 12+log(O/H) ~ 8, place these galaxies in an intermediate regime: higher than the very low ratios expected from supernova-driven dust production, but still below the levels attained once efficient grain growth dominates. These values indicate a transition phase of dust mass assembly, likely reflecting the onset of grain growth via metal accretion under accelerated evolution in the proto-cluster core.

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Hideki Umehata, Yoichi Tamura, Yoshinobu Fudamoto, Yurina Nakazato, Daniel Ceverino, Naoki Yoshida, Akio K. Inoue, Ryota Ikeda, Yuma Sugahara, Shutaro Inui, Santiago Arribas, Tom Bakx, Masato Hagimoto, Takuya Hashimoto, Luis Colina, Yi W. Ren, Wataru Osone, Alejandro Crespo Gomez, Ken Mawatari, Javier Alvarez-Marquez. 2025-10-13. ELPIS: Accelerated metal and dust enrichment in a proto-cluster core at $z\approx8$. https://arxiv.org/abs/2510.11788

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