Extreme Enrichment at Cosmic Dawn: Three Fe II -strong Quasars at z > 6 from the JWST Aether Survey

Abstract We present three outliers on the quasar main sequence at z > 6, as revealed by JWST/NIRSpec integral field unit (IFU) observations from the Aether survey, a program targeting ∼200 quasars at cosmic dawn. The quasars, J0216−5226, J0320−3521, and J1429+5447, exhibit exceptionally strong Fe ii emission and weak H β and [O iii ] lines, indicating rapid chemical enrichment within the first Gyr of cosmic history. Their Fe ii strengths ( R Fe II, λ 4570 ≡ EW Fe II /EW H β ) range between ∼2.5 and 3.6, placing them among the top ∼3% of Sloan Digital Sky Survey quasars at (0 ≲ z ≲ 1). The H α emission lines of J0216−5226 and J1429+5447 imply black hole masses of ∼1–7 × 10 9 M ⊙ with λ Edd ∼ 0.1–0.6, comparable to typical high- z quasars, although virial black hole masses may be systematically overestimated in strong Fe ii emitters. In contrast, J0320−3521 hosts a lower-mass black hole of ∼0.2–2 × 10 9 M ⊙ , suggesting possible super-Eddington rate accretion with λ Edd ∼ 0.5–6.0. The IFU data of J0320−3521 reveal a distinct emission-line region at a projected distance of ∼1.5 kpc, consistent with either an interacting companion or ionized gas associated to the quasar. We further identify a complex environment around J1429+5447, including two candidate companion galaxies or extended ionized gas structures. These quasars with bright emission-line regions, J0320−3521 and J1429+5447, are radio-loud sources, while J0216−5226 remains undetected in radio ( R 5GHz, 3 σ ≲ 4). Together, these results confirm previous findings that highly enriched, rapidly growing black holes were already in place at cosmic dawn. Despite the small sample size, our results further highlight the diversity in environment and radio-jet properties among quasars that otherwise share the same extreme region of the quasar fundamental plane.

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Journal
The Astrophysical Journal
Published
2026-10-26
DOI
https://doi.org/10.3847/1538-4357/aea8f5
Primary Topic
Galaxies: Formation, Evolution, Phenomena
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article
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article

Extreme Enrichment at Cosmic Dawn: Three Fe II -strong Quasars at z > 6 from the JWST Aether Survey

Fabian Walter, Thales A. Gutcke, Hyewon Suh, M. Bischetti et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

Extreme Enrichment at Cosmic Dawn: Three Fe II -strong Quasars at z > 6 from the JWST Aether Survey

Fabian Walter, Thales A. Gutcke, Hyewon Suh, M. Bischetti, F. Loiacono, S. Gallerani, Aaron J. Barth, Fabrizio Arrigoni Battaia, S. Belladitta, J. Wolf, Hyunseop Choi, Feige Wang, Yoshiki Matsuoka, Chiara Mazzucchelli, Anna–Christina Eilers, Eduardo Bañados, Emanuele Paolo Farina, A. J. Gloudemans, Dominika Ďurovčíková, L. Ighina, Silvia Onorato, Klaudia Protušová, Jie Yang, Brian Clark Lemaux, Roberto Decarli
article en

Abstract

Abstract We present three outliers on the quasar main sequence at z > 6, as revealed by JWST/NIRSpec integral field unit (IFU) observations from the Aether survey, a program targeting ∼200 quasars at cosmic dawn. The quasars, J0216−5226, J0320−3521, and J1429+5447, exhibit exceptionally strong Fe ii emission and weak H β and [O iii ] lines, indicating rapid chemical enrichment within the first Gyr of cosmic history. Their Fe ii strengths ( R Fe II, λ 4570 ≡ EW Fe II /EW H β ) range between ∼2.5 and 3.6, placing them among the top ∼3% of Sloan Digital Sky Survey quasars at (0 ≲ z ≲ 1). The H α emission lines of J0216−5226 and J1429+5447 imply black hole masses of ∼1–7 × 10 9 M ⊙ with λ Edd ∼ 0.1–0.6, comparable to typical high- z quasars, although virial black hole masses may be systematically overestimated in strong Fe ii emitters. In contrast, J0320−3521 hosts a lower-mass black hole of ∼0.2–2 × 10 9 M ⊙ , suggesting possible super-Eddington rate accretion with λ Edd ∼ 0.5–6.0. The IFU data of J0320−3521 reveal a distinct emission-line region at a projected distance of ∼1.5 kpc, consistent with either an interacting companion or ionized gas associated to the quasar. We further identify a complex environment around J1429+5447, including two candidate companion galaxies or extended ionized gas structures. These quasars with bright emission-line regions, J0320−3521 and J1429+5447, are radio-loud sources, while J0216−5226 remains undetected in radio ( R 5GHz, 3 σ ≲ 4). Together, these results confirm previous findings that highly enriched, rapidly growing black holes were already in place at cosmic dawn. Despite the small sample size, our results further highlight the diversity in environment and radio-jet properties among quasars that otherwise share the same extreme region of the quasar fundamental plane.

The Astrophysical JournalVol. 1011(1)
University of Pisa (IT), University of Hawaii System (US), Scuola Normale Superiore (IT), Heidelberg University (DE), University of Michigan (US), University of California System (US), Max Planck Institute for Astrophysics (DE), Max Planck Institute for Astronomy (DE), Center for Astrophysics Harvard & Smithsonian (US), NSF NOIRLab (US), Ehime University (JP), Osservatorio di Astrofisica e Scienza dello Spazio (IT), International Gemini Observatory (US), Massachusetts Institute of Technology (US), National Institute for Astrophysics (IT), Universidad Diego Portales (CL)
Openalex Percentile: Top 14%
Galaxies: Formation, Evolution, Phenomena
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