A gas-enshrouded and gas-reddened black hole at cosmic dawn

Rohan P Naidu^{1

2}, Jorryt Matthee³, Harley Katz⁴, Anna de Graaff⁵, Pascal A Oesch^{6

7

8}, Aaron Smith⁹, Jenny E Greene¹⁰, Gabriel Brammer^{7

8}, Andrea Weibel⁶, Raphael Hviding⁵, John Chisholm¹¹, Ivo Labbé¹², Robert A Simcoe¹³, Callum Witten⁶, Wendy Q Sun¹³, Hakim Atek¹⁴, Josephine F W Baggen¹⁵, Sirio Belli¹⁶, Rachel Bezanson¹⁷, Leindert A Boogaard¹⁸, Sownak Bose¹⁹, Rychard J Bouwens¹⁸, Alba Covelo-Paz⁶, Pratika Dayal²⁰, Yoshinobu Fudamoto²¹, Lukas J Furtak²², Emma Giovinazzo⁶, Andy Goulding¹⁰, Max Gronke²³, Kasper E Heintz^{6

7

8}, Michaela Hirschmann²⁴, Garth Illingworth²⁵, Akio K Inoue^{26

27}, Benjamin D Johnson²⁸, Joel Leja^{29

30

31}, Ecaterina Leonova³², Ian McConachie³³, Michael V Maseda³³, Priyamvada Natarajan^{15

34

35}, Erica Nelson³⁶, David J Setton¹⁰, Irene Shivaei³⁷, David Sobral^{38

39}, Mauro Stefanon^{40

41}, Sandro Tacchella^{42

43}, Sune Toft^{7

8}, Alberto Torralba³, Pieter van Dokkum³⁴, Arjen van der Wel⁴⁴, Marta Volonteri¹⁴, Fabian Walter⁵, Bingjie Wang^{29

30

31}, Darach Watson^{7

8}, Katherine Whitaker^{7

45}

Affiliations

¹ MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA, USA. rnaidu@hawaii.edu.
² Institute for Astronomy, University of Hawai'i, Honolulu, HI, USA. rnaidu@hawaii.edu.
³ Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.
⁴ Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA.
⁵ Max-Planck-Institut für Astronomie, Heidelberg, Germany.
⁶ Department of Astronomy, University of Geneva, Geneva, Switzerland.
⁷ Cosmic Dawn Center (DAWN), Copenhagen, Denmark.
⁸ Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
⁹ Department of Physics, The University of Texas at Dallas, Richardson, TX, USA.
¹⁰ Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA.
¹¹ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA.
¹² Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, Victoria, Australia.
¹³ MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA, USA.
¹⁴ Institut d'Astrophysique de Paris, CNRS, Sorbonne Université, Paris, France.
¹⁵ Department of Astronomy, Yale University, New Haven, CT, USA.
¹⁶ Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna, Italy.
¹⁷ Department of Physics and Astronomy and PITT PACC, University of Pittsburgh, Pittsburgh, PA, USA.
¹⁸ Leiden Observatory, Leiden University, Leiden, The Netherlands.
¹⁹ Institute for Computational Cosmology, Department of Physics, Durham University, Durham, UK.
²⁰ Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands.
²¹ Center for Frontier Science, Chiba University, Chiba, Japan.
²² Department of Physics, Ben-Gurion University of the Negev, Be'er-Sheva, Israel.
²³ Max Planck Institute for Astrophysics, Garching, Germany.
²⁴ Institute of Physics, Lab for galaxy evolution and spectral modelling, EPFL, Observatory of Sauverny, Geneva, Switzerland.
²⁵ Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA, USA.
²⁶ Department of Physics, School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
²⁷ Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
²⁸ Center for Astrophysics - Harvard and Smithsonian, Cambridge, MA, USA.
²⁹ Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA, USA.
³⁰ Institute for Computational and Data Sciences, The Pennsylvania State University, University Park, PA, USA.
³¹ Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA, USA.
³² GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics, University of Amsterdam, Amsterdam, The Netherlands.
³³ Department of Astronomy, University of Wisconsin-Madison, Madison, WI, USA.
³⁴ Department of Physics, Yale University, New Haven, CT, USA.
³⁵ Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT, USA.
³⁶ Department for Astrophysical and Planetary Science, University of Colorado, Boulder, CO, USA.
³⁷ Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain.
³⁸ BNP Paribas Corporate & Institutional Banking, Lisbon, Portugal.
³⁹ Departamento de Física, Faculdade de Ciencias, Universidade de Lisboa, Lisbon, Portugal.
⁴⁰ Departament d'Astronomia i Astrofísica, Universitat de València, València, Spain.
⁴¹ Unidad Asociada CSIC 'Grupo de Astrofísica Extragaláctica y Cosmología' (Instituto de Física de Cantabria - Universitat de València), València, Spain.
⁴² Kavli Institute for Cosmology, University of Cambridge, Cambridge, UK.
⁴³ Cavendish Laboratory, University of Cambridge, Cambridge, UK.
⁴⁴ Sterrenkundig Observatorium, Universiteit Gent, Ghent, Belgium.
⁴⁵ Department of Astronomy, University of Massachusetts, Amherst, MA, USA.

PMID: 42587117
PMCID: PMC13468124
DOI: 10.1038/s41586-026-10846-4

A gas-enshrouded and gas-reddened black hole at cosmic dawn

Rohan P Naidu et al. Nature. 2026 Aug.

. 2026 Aug;656(8127):329-333.

doi: 10.1038/s41586-026-10846-4. Epub 2026 Aug 12.

Authors

Affiliations

¹ MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA, USA. rnaidu@hawaii.edu.
² Institute for Astronomy, University of Hawai'i, Honolulu, HI, USA. rnaidu@hawaii.edu.
³ Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.
⁴ Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA.
⁵ Max-Planck-Institut für Astronomie, Heidelberg, Germany.
⁶ Department of Astronomy, University of Geneva, Geneva, Switzerland.
⁷ Cosmic Dawn Center (DAWN), Copenhagen, Denmark.
⁸ Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
⁹ Department of Physics, The University of Texas at Dallas, Richardson, TX, USA.
¹⁰ Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA.
¹¹ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA.
¹² Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, Victoria, Australia.
¹³ MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA, USA.
¹⁴ Institut d'Astrophysique de Paris, CNRS, Sorbonne Université, Paris, France.
¹⁵ Department of Astronomy, Yale University, New Haven, CT, USA.
¹⁶ Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna, Italy.
¹⁷ Department of Physics and Astronomy and PITT PACC, University of Pittsburgh, Pittsburgh, PA, USA.
¹⁸ Leiden Observatory, Leiden University, Leiden, The Netherlands.
¹⁹ Institute for Computational Cosmology, Department of Physics, Durham University, Durham, UK.
²⁰ Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands.
²¹ Center for Frontier Science, Chiba University, Chiba, Japan.
²² Department of Physics, Ben-Gurion University of the Negev, Be'er-Sheva, Israel.
²³ Max Planck Institute for Astrophysics, Garching, Germany.
²⁴ Institute of Physics, Lab for galaxy evolution and spectral modelling, EPFL, Observatory of Sauverny, Geneva, Switzerland.
²⁵ Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA, USA.
²⁶ Department of Physics, School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
²⁷ Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
²⁸ Center for Astrophysics - Harvard and Smithsonian, Cambridge, MA, USA.
²⁹ Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA, USA.
³⁰ Institute for Computational and Data Sciences, The Pennsylvania State University, University Park, PA, USA.
³¹ Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA, USA.
³² GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics, University of Amsterdam, Amsterdam, The Netherlands.
³³ Department of Astronomy, University of Wisconsin-Madison, Madison, WI, USA.
³⁴ Department of Physics, Yale University, New Haven, CT, USA.
³⁵ Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT, USA.
³⁶ Department for Astrophysical and Planetary Science, University of Colorado, Boulder, CO, USA.
³⁷ Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain.
³⁸ BNP Paribas Corporate & Institutional Banking, Lisbon, Portugal.
³⁹ Departamento de Física, Faculdade de Ciencias, Universidade de Lisboa, Lisbon, Portugal.
⁴⁰ Departament d'Astronomia i Astrofísica, Universitat de València, València, Spain.
⁴¹ Unidad Asociada CSIC 'Grupo de Astrofísica Extragaláctica y Cosmología' (Instituto de Física de Cantabria - Universitat de València), València, Spain.
⁴² Kavli Institute for Cosmology, University of Cambridge, Cambridge, UK.
⁴³ Cavendish Laboratory, University of Cambridge, Cambridge, UK.
⁴⁴ Sterrenkundig Observatorium, Universiteit Gent, Ghent, Belgium.
⁴⁵ Department of Astronomy, University of Massachusetts, Amherst, MA, USA.

PMID: 42587117
PMCID: PMC13468124
DOI: 10.1038/s41586-026-10846-4

Abstract

The physical processes that led to the formation of billion-solar-mass black holes within the first 700 million years of cosmic time, a period known as cosmic dawn, remain a puzzle¹. Several theoretical scenarios have been proposed to seed and rapidly grow black holes^2-4, but direct observations of these mechanisms remain elusive. Here we present a source 660 million years after the Big Bang that exhibits singular properties: among the largest hydrogen Balmer breaks reported at any redshift, broad multi-peaked Hβ emission, and Balmer line absorption in several transitions. We model this source as an enshrouded black hole in which the Balmer break and absorption features are a result of extremely dense, turbulent gas forming a dust-free envelope around a supermassive black hole^5,6. This source may provide evidence of an early black hole embedded in dense gas-a theoretical configuration proposed to rapidly grow black holes by super-Eddington accretion^7,8. Radiation from the black hole seems to dominate almost all observed light, leaving limited room for contribution from its host galaxy. If the source merged with its brighter neighbour, it would resemble the recently discovered 'little red dots' with perplexing spectral energy distributions^9-11. The redness of the black hole is due to gas, not dust^12,13, and scattering, not kinematics, gives rise to the complex line shapes and luminosities-black hole masses of these sources may therefore be overestimated by orders of magnitude.

PubMed Disclaimer

Conflict of interest statement

Competing interests: The authors declare no competing interests.

Figures

**Fig. 1. JWST imaging and spectroscopy of MoM-BH*-1.**
a, The 3 × 3″ NIRCam and MIRI images of MoM-BH*-1 spanning 0.9–18 μm. The source is point-like and detected (>3σ) only in the F356W, F444W and F770W bands, apparently disappearing in the bluer bands. b, The NIRSpec prism spectrum (dark blue) shows that the disappearance is due to an enormous Balmer break. Key spectral features such as the Balmer series are marked with dashed lines. c, The 1″ RGB image shows the almost identical slit positions with which the source was observed with the prism (b) and G395M grating (d). d, Deep absorption features in Hγ and Hβ are evident in the G395M grating spectra. The location of the central absorption is consistent across both Hβ and Hγ as well as across the prism and grating spectra. The systemic redshift is based on the [Oiii] 4,960, 5,008 Å doublet. A representative draw from the emission line model posterior is plotted in orange (Methods).

**Fig. 2. The exceptional Balmer break strength of MoM-BH*-1.**
a, Contrast of MoM-BH*-1 against a quiescent galaxy and an LRD that lie at a similar redshift (z ≈ 7) and exhibit some of the strongest Balmer breaks reported yet (about 3). The two wavelength windows we use to compute break strengths are highlighted in green—these windows ([3,620–3,720] Å and [4,000–4,100] Å) are free of strong emission lines and are particularly suited for studying high-redshift galaxies. The spectra shown here are normalized in the blue window—flux in this window is detected at >4.5σ for MoM-BH*-1. b, Comparison of break strengths of quiescent galaxies, LRDs with Balmer breaks and stacks of star-forming galaxies at similar redshifts as MoM-BH*-1. The dashed line represents the maximum break strength expected for a dust-free stellar population and a Chabrier initial mass function. MoM-BH*-1 displays the strongest Balmer break at these redshifts and lies well beyond this stellar population maximum. The asymmetric and higher uncertainty on the break strength in MoM-BH*-1 is due to the relatively fainter flux and lower signal-to-noise ratio (about 3) in the blue window.

**Fig. 3. Comparison with a mock spectrum of a gas-enshrouded BH model.**
Schematic of an SMBH with a 40 au column of dense gas—the continuum is produced in hot regions close to the SMBH, whereas absorption, scattering and further emission occur in the dense gas atmosphere. The data (dark blue) are binned (3×) to emphasize that the continuum shape that our fiducial model (pink, with noise as per error spectrum) provides is an excellent match. The model is selected to reproduce the Balmer break strength and Balmer line EWs, while also matching the UV-faintness and MIRI long-wavelength data without having to invoke different mechanisms for lines and continuum. The narrow [Oiii] emission and additional UV luminosity plausibly arise from the faint host galaxy and are not captured by the model (Fig. 4). The excess flux around H_∞ is a Cloudy model artefact because of modelling with a finite number of hydrogen levels.

**Fig. 4. Explanation of LRDs as gas-enshrouded BHs embedded in comparably bright host galaxies.**
a,b, MoM-BH*-1 (blue) lies close to a M_⋆ ≈ 10^9.5 M_⊙ galaxy at the same redshift (grey). These sources are expected to merge in about 100 Myr, and their superimposed spectrum (offset for clarity; a) and photometry (1″ × 1″ NIRCam stamps; b) is shown in red. The combined spectrum bears a striking resemblance to the typical LRD, displaying a V-shaped SED, an inflection around H_∞ = 3,646 Å and a complex Hβ profile with a broad component. The NIRCam stamps demonstrate compactness in the rest-optical and an extended structure in the rest-UV. Although the galaxy is dominant in the rest-UV, the BH outshines it towards the rest-optical.

**Extended Data Fig. 1. Simultaneous emission line fits to the prism (Panel a.) and grating (Panel b.) spectra.**
100 draws from the posterior are shown in orange. The consistency of features across both modes inspires confidence in their reality. For example, the detailed structure of the Hβ line – a central absorber, extremely broad wings, and absorption even in the wings – recurs in both panels. Similarly, the existence of narrow [Oiii] 5008 Å emission would be difficult to discern in either mode by itself, but is recovered in the joint fit.

**Extended Data Fig. 2. The remarkable symmetry of the Hβ line profile points to a symmetric configuration of absorbing gas.**
Here we compare the observed line profile (Panel a, blue) to a line profile mirrored around the systemic redshift derived from [Oiii] (Panel b, orange). In Panel c we co-add these spectra. These profiles display peaks (± 1000 km s⁻¹, and perhaps also ± 2400 km s⁻¹) and troughs (± 1500 km s⁻¹; see absorber locations in Extended Data Table 2) at similar velocities. This potential symmetry has important implications. First, it means the recovered systemic redshift from [Oiii] is robust. Furthermore, these features are highly unlikely to be the result of random absorption systems or inflows/outflows that are fortuitously aligned at the same positive and negative velocities. Instead, this alignment suggests the presence of a symmetric absorbing structure (e.g., shells of gas).

**Extended Data Fig. 3. Comparison of fiducial model against long-wavelength data.**
Not only is this virtually dust-free model (A_V = 0.15 mag) able to explain the strong Balmer break and UV-weakness, but also the ‘turn-over’ at infrared wavelengths traced by MIRI (shown in green) and generically reported for the LRDs. The model spectrum (salmon) is normalized to the NIRCam fluxes that are closest to the epoch of the MIRI observations (see text and Extended Data Fig. 6 for discussion of variability). An important implication of this SED shape is that the bolometric luminosity is effectively entirely emitted in the rest-optical and near-IR.

**Extended Data Fig. 4. Cross-sectional view of the best-fit Cloudy model.**
Emergent spectra as observed at various depths are overlaid in the main panel – the incident power-law continuum (black, r/R_cloud ≈ 0) is reprocessed such that a deep Balmer break and absorption features are imparted (light blue, r/R_cloud ≈ 1). The inset panel in the top-left shows the fractional density of ionized gas (H⁺), neutral gas (H), and the n = 1 and n = 2 levels – crucially, a significant n = 2 population exists to produce deep Balmer absorption. Note that there is no dust in the model, and we apply dust only as a post-processing step. The bottom-right inset panel shows where the observed Hβ line arises from – remarkably, Hβ in emission is produced close to the surface (e.g., due to collisional effects) and has little to do with the kinematics of the interior – this has critical implications for BH mass estimates based on Balmer lines.

**Extended Data Fig. 5. Resonant Balmer scattering?.**
**Panel a**. Through simple radiative transfer calculations with a shell model we demonstrate that Hβ behaves like Lyα if radiative decay transitions into the 2p state are suppressed. The trends that are well-known in the Lyα literature and relevant to our situation hold here. A narrow intrinsic line is scattered into double peaks. Dust weakens the blue peak preferentially, inflows/outflows boost one peak relative to another, and static shells produce equally strong peaks. **Panel b**. We model the two main peaks of the MoM-BH*-1 profile with a static, dust-free shell. This toy model does not capture the full extent of the broad wings which implies models with a more complicated geometry need to be explored, especially with higher S/N data.

**Extended Data Fig. 6. Testing variability in MoM-BH*-1.**
**Panel a**. Synthesized NIRCam photometry from the three epochs of observations are compared (pink, gold, blue) against the prism spectrum (navy). Non-detections in the NIRCam imaging (2σ upper limits) are shown as pink triangles. Note that the spectrum is generally deeper than the photometry, particularly in the rest-UV. **Panel b**. The observations span 56 days in the rest-frame of the source. While virtually every source in the prism observations has lost flux relative to the F444W imaging due to slit-losses (1σ contours for median ratio shown in grey), MoM-BH*-1 has brightened by ≈ 30%. **Panel c**. MoM-BH*-1 is the only source across both observed masks in the UDS that has brightened by this degree relative to its NIRCam photometry. The ratio shown here is the median ratio of the flux synthesized from the prism and directly measured by NIRCam in the four LW filters observed by the PRIMER survey in August 2023 (F277W, F356W, F410M, and F444W). **Panel d**. This variability signal is unlikely to be due to an overestimated extraction aperture (σ) in the NIRSpec reduction pipeline. The compact flux radius of the source measured from the imaging is commensurate with the extraction aperture used for the spectra.

See this image and copyright information in PMC

References

1. Wang, F. et al. A luminous quasar at redshift 7.642. Astrophys. J. Lett.907, L1 (2021). - DOI
1. Woods, T. E. et al. Titans of the early Universe: the Prato statement on the origin of the first supermassive black holes. Publ. Astron. Soc. Aust.36, e027 (2019). - DOI
1. Inayoshi, K., Visbal, E. & Haiman, Z. The assembly of the first massive black holes. Annu. Rev. Astron. Astrophys.58, 27–97 (2020). - DOI
1. Volonteri, M., Habouzit, M. & Colpi, M. The origins of massive black holes. Nat. Rev. Phys.3, 732–743 (2021). - DOI
1. Inayoshi, K. & Maiolino, R. Extremely dense gas around little red dots and high-redshift active galactic nuclei: a non-stellar origin of the Balmer break and absorption features. Astrophys J. Lett. 980, L27, (2025).

LinkOut - more resources

Full Text Sources
- Nature Publishing Group
- PubMed Central

Save citation to file

Email citation

Add to Collections

Add to My Bibliography

Your saved search

Create a file for external citation management software

Your RSS Feed

A gas-enshrouded and gas-reddened black hole at cosmic dawn

Affiliations

A gas-enshrouded and gas-reddened black hole at cosmic dawn

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

LinkOut - more resources

Full Text Sources