The case for super-Eddington accretion in JWST broad-line active galactic nuclei during the first billion years

A multitude of studies of data recorded by the James Webb Space Telescope (JWST) reveal a surprising overabundance of over-massive accreting supermassive black holes, leading to a deepening tension between theory and observation for the first billion years of cosmic time. Across X-ray to infrared wavelengths, models built on pre-JWST predictions fail to easily reproduce the observed signatures of active galactic nuclei (or lack thereof), driving uncertainty around the true nature of these sources. Here, using a sample of JWST active galactic nuclei identified via their broadened Hα emission and covered by the deepest X-ray surveys, we find neither any measurable X-ray emission nor any detection of high-ionization emission lines frequently associated with accreting supermassive black holes. We propose that these sources are accreting at or beyond the Eddington limit, which reduces the need for the efficient production of heavy supermassive black hole seeds at cosmic dawn. Using a theoretical model of super-Eddington accretion, we can produce the observed relative dearth of both X-ray and ultraviolet emission, as well as the high Balmer decrements, without the need for substantial dust attenuation. This work indicates that super-Eddington accretion is easily achieved throughout the early Universe, and further study is required to determine what environments are required to trigger this mode of black hole growth. A sample of X-ray-weak active galactic nuclei at high redshift may be accreting above the Eddington limit. This could explain their large masses without the need for heavy supermassive black hole seeds at cosmic dawn.

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Publication Details

Journal
Nature Astronomy
Published
2026-04-07
DOI
https://doi.org/10.1038/s41550-026-02813-w
Primary Topic
Astrophysical Phenomena and Observations
Type
article
Field-Weighted Citation Impact
0.00

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article

The case for super-Eddington accretion in JWST broad-line active galactic nuclei during the first billion years

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Astrophysical Phenomena and Observations
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The case for super-Eddington accretion in JWST broad-line active galactic nuclei during the first billion years

Fabio Pacucci, Danielle A. Berg, M. Chiaberge, Rebecca L. Larson, M. Hirschmann, Kelly E. Whalen, Aidan P. Cloonan, Kristen Garofali, Chris T. Richardson, M. Stiavelli, R. Gilli, A. Ptak, Ryan Endsley, Colin Norman, H. Akins, Jed McKinney, Francesca Civano, Vasily Kokorev, Taylor A. Hutchison, Erini Lambrides, Steven Gillman, Jeyhan S. Kartaltepe, John Chisholm, Arianna S. Long, Dale D. Kocevski, Andreas L. Faisst
article en

Abstract

A multitude of studies of data recorded by the James Webb Space Telescope (JWST) reveal a surprising overabundance of over-massive accreting supermassive black holes, leading to a deepening tension between theory and observation for the first billion years of cosmic time. Across X-ray to infrared wavelengths, models built on pre-JWST predictions fail to easily reproduce the observed signatures of active galactic nuclei (or lack thereof), driving uncertainty around the true nature of these sources. Here, using a sample of JWST active galactic nuclei identified via their broadened Hα emission and covered by the deepest X-ray surveys, we find neither any measurable X-ray emission nor any detection of high-ionization emission lines frequently associated with accreting supermassive black holes. We propose that these sources are accreting at or beyond the Eddington limit, which reduces the need for the efficient production of heavy supermassive black hole seeds at cosmic dawn. Using a theoretical model of super-Eddington accretion, we can produce the observed relative dearth of both X-ray and ultraviolet emission, as well as the high Balmer decrements, without the need for substantial dust attenuation. This work indicates that super-Eddington accretion is easily achieved throughout the early Universe, and further study is required to determine what environments are required to trigger this mode of black hole growth. A sample of X-ray-weak active galactic nuclei at high redshift may be accreting above the Eddington limit. This could explain their large masses without the need for heavy supermassive black hole seeds at cosmic dawn.

Nature Astronomy
California Institute of Technology (US), Space Telescope Science Institute (US), Goddard Space Flight Center (US), Woodwell Climate Research Center (US), Harvard University (US), Johns Hopkins University (US), Rochester Institute of Technology (US), Elon University (US), University of Washington (US), University of Massachusetts Amherst (US), Colby College (US), Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna (IT), Center for Astrophysics Harvard & Smithsonian (US), Infrared Processing and Analysis Center (US), Osservatorio di Astrofisica e Scienza dello Spazio, École Polytechnique Fédérale de Lausanne (CH), The University of Texas at Austin (US)
National Aeronautics and Space Administration, Oak Ridge Associated Universities, Space Telescope Science Institute, Goddard Space Flight Center
Openalex Percentile: Top 18%
Astrophysical Phenomena and Observations
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