The Multiphase CGM in the Epoch of Reionization: CII and CIV absorbers around [OIII] Emitters

@misc{piscitelli2026multiphase,
  title = {{The Multiphase CGM in the Epoch of Reionization: CII and CIV absorbers around [OIII] Emitters}},
  author = {C. Piscitelli and V. D'Odorico and M. Galbiati and M. Bischetti and G. Cupani and R. Dutta and S. Cantalupo and S. Di Stefano and S. T. Guida and K. Knudsen and C. Mazzucchelli and L. Paquereau and L. Pentericci and R. Rana and F. Ricci and F. Salvestrini and A. Tortosa and A. Travascio and C. Vignali and L. Zappacosta},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.15547},
  eprint = {2609.15547},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.15547},
  note = {CC BY-NC-ND 4.0},
}

TY  - UNPB
TI  - The Multiphase CGM in the Epoch of Reionization: CII and CIV absorbers around [OIII] Emitters
AU  - C. Piscitelli
AU  - V. D'Odorico
AU  - M. Galbiati
AU  - M. Bischetti
AU  - G. Cupani
AU  - R. Dutta
AU  - S. Cantalupo
AU  - S. Di Stefano
AU  - S. T. Guida
AU  - K. Knudsen
AU  - C. Mazzucchelli
AU  - L. Paquereau
AU  - L. Pentericci
AU  - R. Rana
AU  - F. Ricci
AU  - F. Salvestrini
AU  - A. Tortosa
AU  - A. Travascio
AU  - C. Vignali
AU  - L. Zappacosta
PY  - 2026
DA  - 2026/09/18
PB  - arXiv
DO  - 10.48550/arxiv.2609.15547
UR  - https://arxiv.org/abs/2609.15547
AB  - We investigate the multiphase circumgalactic medium (CGM) during the Epoch of Reionization (EoR, z>6) by cross-correlating cool- CII and warm-ionized CIV absorption systems with star-forming [OIII] emitters. JWST/NIRCam wide-field slitless spectroscopy from the EIGER survey is combined with medium- and high-resolution optical/NIR spectra of six background quasars, including new VLT/X-Shooter observations of PSO J159-02. We analyze the relation between 16 CII and 14 CIV absorbers (log(N) > 13.0) and 136 galaxies, within an impact parameter of R_⊥ ≤ 1000 pkpc and a line-of-sight separation of Δv ≤ 500 km/s. We detect a statistically significant excess of both ions around galaxies compared to a randomized background. We observe that the CIV covering fraction remains enhanced up to ∼ 1 pMpc, whereas CII drops to the background level beyond ∼ 0.5 pMpc, demonstrating that the warm-ionized phase is more spatially extended than cooler gas. Jointly, the 3D galaxy-absorber spatial clustering is significantly weaker than the galaxy-galaxy auto-correlation. This provides direct physical evidence that early carbon enrichment is not confined to the virial radius of massive star-forming systems; rather, a substantial fraction of these metals permeates the diffuse intergalactic medium (IGM) or is injected by a widespread population of faint, undetected dwarf galaxies. Finally, we note a rapid radial decline of the CIV covering fraction compared with lower redshift samples at z<2 and z∼3−4 pointing out an evolving CGM ionization structure where early metals reside predominantly in lower ionization states. In conclusion, we determine a conservative lower limit for the observed carbon mass of M_CII + CIV ≥ 2.8 × 10^6 M_⊙ within 300 pkpc.
ER  -