The Deepest GLIMPSE of a Dense Gas Cocoon Enshrouding a Little Red Dot

@article{kokorev2026deepest,
  title = {{The Deepest GLIMPSE of a Dense Gas Cocoon Enshrouding a Little Red Dot}},
  author = {Vasily Kokorev and John Chisholm and Rohan P. Naidu and Seiji Fujimoto and Hakim Atek and Gabriel Brammer and Steven L. Finkelstein and Hollis B. Akins and Danielle A. Berg and Lukas J. Furtak and Qinyue Fei and Tiger Yu-Yang Hsiao and Ivo Labbé and Jorryt Matthee and Julián B. Muñoz and Pascal A. Oesch and Richard Pan and Pierluigi Rinaldi and Alberto Saldana-Lopez and D. Schaerer and Marta Volonteri and Adi Zitrin},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = jun,
  doi = {10.3847/1538-4357/ae4ed7},
  url = {https://doi.org/10.3847/1538-4357/ae4ed7},
  note = {CC BY},
}

TY  - JOUR
TI  - The Deepest GLIMPSE of a Dense Gas Cocoon Enshrouding a Little Red Dot
AU  - Vasily Kokorev
AU  - John Chisholm
AU  - Rohan P. Naidu
AU  - Seiji Fujimoto
AU  - Hakim Atek
AU  - Gabriel Brammer
AU  - Steven L. Finkelstein
AU  - Hollis B. Akins
AU  - Danielle A. Berg
AU  - Lukas J. Furtak
AU  - Qinyue Fei
AU  - Tiger Yu-Yang Hsiao
AU  - Ivo Labbé
AU  - Jorryt Matthee
AU  - Julián B. Muñoz
AU  - Pascal A. Oesch
AU  - Richard Pan
AU  - Pierluigi Rinaldi
AU  - Alberto Saldana-Lopez
AU  - D. Schaerer
AU  - Marta Volonteri
AU  - Adi Zitrin
PY  - 2026
DA  - 2026/06/10
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae4ed7
UR  - https://doi.org/10.3847/1538-4357/ae4ed7
AB  - The detection of strong Balmer breaks and absorption features in Little Red Dots (LRDs) suggests they host active galactic nuclei embedded within dense gas envelopes, potentially powered by super-Eddington accretion. We present GLIMPSE-17775, a luminous ( L bol ∼ 10 45 erg s −1 ) LRD at z = 3.501 behind Abell S1063 ( μ ∼ 2), observed with deep JWST/NIRCam and a ∼20 hr (80 hr delensed) NIRSpec G395M spectrum. The data reveal over 40 emission and absorption features, including a rich forest of low-ionization Fe ii lines and numerous broad hydrogen recombination transitions. We use this depth to test the dense-gas interpretation through five independent diagnostics. Nearly all permitted lines show exponential wings with consistent FWHM, a signature of Thomson scattering requiring n e ≳ 10 8 cm −3 . Adopting this width yields M BH ∼ 10 6.7 M ⊙ , a factor of 10 lower than Gaussian fits, and λ Edd ∼ 1.8. Additional diagnostics support the same picture: a pronounced Balmer break ( f ν ,4050 / f ν ,3670 = 2.0 ± 0.1), enhanced He i λ 7065 and λ 10830 with P-Cygni absorption, Bowen-fluorescent O i λ 8446– λ 11290 emission requiring Ly β pumping, and 16 Fe ii lines matching fluorescence models. These features indicate a dense ( n ∼ 10 8 cm −3 ), partially ionized cocoon where scattering and fluorescence dominate line formation, providing strong evidence that at least some LRDs are powered by super-Eddington black hole growth in the early Universe.
SN  - 0004-637X
SN  - 1538-4357
ER  -