First-star imprints in a metal-poor galaxy overdensity near the end of reionization
Abstract
The first generation of stars, known as Population III (Pop III), formed from primordial gas consisting solely of hydrogen and helium and is believed to have emerged only a few hundred million years after the Big Bang. Detecting the chemical enrichment of metal-poor circumgalactic gas offers a promising way to trace the enrichment signature of Pop III stars. Along the sightline to the quasar SDSS J0100+2802, a metal absorber at z = 5.945, showing over-abundant carbon and silicon compared to solar, has been reported to be consistent with the enrichment pattern of Pop III stars. With the James Webb Space Telescope, we report the discovery of an unusually metal-poor galaxy overdensity of 17 members (mean metallicity ≈ 3% solar) near this metal absorber, which is ∼ 0.4 dex more metal-poor than coeval galaxies in similarly overdense environments. This less chemically evolved system may have provided favorable conditions for preserving the absorption signatures of Pop III enrichment. We infer a minimum dark matter halo of log(Mh,min/M⊙)=10.68+0.93−1.72, supporting late-time Pop III formation at the outskirts of atomic hydrogen cooling halos. Our findings open a promising observational pathway to identify the chemical imprints of the first stars and constrain the conditions for their formation.
Related
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BibTeX
@misc{li2026firststar,
title = {{First-star imprints in a metal-poor galaxy overdensity near the end of reionization}},
author = {Zihao Li and Koki Kakiichi and Lise Christensen and Zheng Cai and Valentina D'Odorico and Jorryt Matthee and Daichi Kashino and Rongmon Bordoloi and Ruari Mackenzie and Trystyn A. M. Berg and Irene Vanni and Stefania Salvadori and Alessandra Venditti and Shiwu Zhang and Sarah E. I. Bosman and Eduardo Bañados and Frederick B. Davies and Xiaohui Fan and Hyunsung D. Jun and Xiangyu Jin and Mingyu Li and Sofía Rojas-Ruiz and Feige Wang and Jinyi Yang and Siwei Zou and Huanian Zhang and Yongda Zhu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.31638},
eprint = {2606.31638},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.31638},
}
RIS
TY - UNPB
TI - First-star imprints in a metal-poor galaxy overdensity near the end of reionization
AU - Zihao Li
AU - Koki Kakiichi
AU - Lise Christensen
AU - Zheng Cai
AU - Valentina D'Odorico
AU - Jorryt Matthee
AU - Daichi Kashino
AU - Rongmon Bordoloi
AU - Ruari Mackenzie
AU - Trystyn A. M. Berg
AU - Irene Vanni
AU - Stefania Salvadori
AU - Alessandra Venditti
AU - Shiwu Zhang
AU - Sarah E. I. Bosman
AU - Eduardo Bañados
AU - Frederick B. Davies
AU - Xiaohui Fan
AU - Hyunsung D. Jun
AU - Xiangyu Jin
AU - Mingyu Li
AU - Sofía Rojas-Ruiz
AU - Feige Wang
AU - Jinyi Yang
AU - Siwei Zou
AU - Huanian Zhang
AU - Yongda Zhu
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2606.31638
UR - https://arxiv.org/abs/2606.31638
AB - The first generation of stars, known as Population III (Pop III), formed from primordial gas consisting solely of hydrogen and helium and is believed to have emerged only a few hundred million years after the Big Bang. Detecting the chemical enrichment of metal-poor circumgalactic gas offers a promising way to trace the enrichment signature of Pop III stars. Along the sightline to the quasar SDSS J0100+2802, a metal absorber at z = 5.945, showing over-abundant carbon and silicon compared to solar, has been reported to be consistent with the enrichment pattern of Pop III stars. With the James Webb Space Telescope, we report the discovery of an unusually metal-poor galaxy overdensity of 17 members (mean metallicity ≈ 3% solar) near this metal absorber, which is ∼ 0.4 dex more metal-poor than coeval galaxies in similarly overdense environments. This less chemically evolved system may have provided favorable conditions for preserving the absorption signatures of Pop III enrichment. We infer a minimum dark matter halo of log(M_h,min/M_⊙)=10.68^+0.93_−1.72, supporting late-time Pop III formation at the outskirts of atomic hydrogen cooling halos. Our findings open a promising observational pathway to identify the chemical imprints of the first stars and constrain the conditions for their formation.
ER -