A dense, metal-rich absorber driven by a heavily dust-obscured galaxy: The direct evidence of CGM enrichment at z∼7

@misc{fei2026dense,
  title = {{A dense, metal-rich absorber driven by a heavily dust-obscured galaxy: The direct evidence of CGM enrichment at $z\sim7$}},
  author = {Qinyue Fei and Seiji Fujimoto and Gabriel Brammer and Lise Christensen and Marianne Vestergaard and Rohan P. Naidu and Robert A. Simcoe and Norman Murray and Luis C. Ho and Ruancun Li and Volker Bromm and Javier Álvarez-Márquez and Hollis B. Akins and Yoshihisa Asada and Simona Di Stefano and Kohei Inayoshi and Vasily Kokorev and Jorryt Matthee and Romain A. Meyer and Ava Polzin and Francesco Valentino and Fabian Walter and Marcel Neeleman and Yunjing Wu and Mengyuan Xiao},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2609.17680},
  eprint = {2609.17680},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.17680},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - A dense, metal-rich absorber driven by a heavily dust-obscured galaxy: The direct evidence of CGM enrichment at z∼7
AU  - Qinyue Fei
AU  - Seiji Fujimoto
AU  - Gabriel Brammer
AU  - Lise Christensen
AU  - Marianne Vestergaard
AU  - Rohan P. Naidu
AU  - Robert A. Simcoe
AU  - Norman Murray
AU  - Luis C. Ho
AU  - Ruancun Li
AU  - Volker Bromm
AU  - Javier Álvarez-Márquez
AU  - Hollis B. Akins
AU  - Yoshihisa Asada
AU  - Simona Di Stefano
AU  - Kohei Inayoshi
AU  - Vasily Kokorev
AU  - Jorryt Matthee
AU  - Romain A. Meyer
AU  - Ava Polzin
AU  - Francesco Valentino
AU  - Fabian Walter
AU  - Marcel Neeleman
AU  - Yunjing Wu
AU  - Mengyuan Xiao
PY  - 2026
DA  - 2026/10/11
PB  - arXiv
DO  - 10.48550/arxiv.2609.17680
UR  - https://arxiv.org/abs/2609.17680
AB  - We report the serendipitous discovery of a dense, metal-enriched circumgalactic medium (CGM) absorber at z=7.03, together with its host galaxy, identified along the sightline toward a red quasar. The absorber exhibits the largest rest-frame equivalent widths and column densities observed to date at z>5, tracing a metal-enriched gaseous halo. Using deep JWST/NIRSpec and NOEMA observations, we characterize the absorber's physical properties and identify its host, ND1, as a vigorously star-forming galaxy at an exceptionally close impact parameter of ~16kpc, so heavily dust-obscured that it is detected only in the longest-wavelength NIRCam bands. Detections of [OIII]λ5007, Hα, and [CII]λ158 μm emission anchor the systemic redshift to z~7.0321, revealing a coherent ~50km/s blueshift of the absorbing gas relative to the host, suggesting outflow-driven metal transport into the halo. The outflow velocity, combined with the measured column density, implies an outflow rate of Ṁ_out=64 M_⊙ yr^−1 and a mass loading factor η=3, indicating an energetic, chemically-enriched wind launched from a dust-obscured starburst. While the overall ionization state and [Mg/Fe] ratio align with empirical cosmic evolutionary trends, the absorber displays an enhanced carbon-to-oxygen ([C/O]) ratio. This abundance pattern suggests the nucleosynthetic yields of Population~III stellar explosions, and aligns with the host's star-formation history extending to z ≳ 8, potentially offering a rare fossil record of primordial metal enrichment. Our findings demonstrate that intense star-formation feedback can rapidly and efficiently pollute the CGM/IGM well into the Epoch of Reionization. The NIR-dark nature of the host further implies that rest-UV surveys may systematically miss the dusty sources that drive CGM- and IGM-scale metal enrichment in the early Universe.
ER  -