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Evidence for heavy-seed origin of early supermassive black holes from a z ≈ 10 X-ray quasar


Observations of quasars reveal that many supermassive black holes (BHs) were in place less than 700 Myr after the Big Bang. However, the origin of the first BHs remains a mystery. Seeds of the first BHs are postulated to be either light (that is, 10−100 M), remnants of the first stars, or heavy (that is, 10−105M), originating from the direct collapse of gas clouds. Here, harnessing recent data from the Chandra X-ray Observatory, we report the detection of an X-ray-luminous massive BH in a gravitationally lensed galaxy identified by the James Webb Space Telescope at redshift z ≈ 10.3 behind the cluster lens Abell 2744. This heavily obscured quasar with a bolometric luminosity of ~5 × 1045 erg s−1 harbours an ~107−108M BH assuming accretion at the Eddington limit. This mass is comparable to the inferred stellar mass of its host galaxy, in contrast to what is found in the local Universe wherein the BH mass is ~0.1% of the host galaxy’s stellar mass. The combination of such a high BH mass and large BH-to-galaxy stellar mass ratio just ~500 Myr after the Big Bang was theoretically predicted and is consistent with a picture wherein BHs originated from heavy seeds.

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Fig. 1: A 4.2σ Chandra X-ray detection of a source co-spatial with UHZ1.
Fig. 2: JWST and Chandra images of UHZ1.
Fig. 3: Chandra X-ray SED and model fits.
Fig. 4: Sketch of the growth of BHs with different initial seed masses and accretion rates.

Data availability

The JWST data of Abell 2744 are publicly available at MAST ( The Chandra data are available upon request from the corresponding author.


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This research has made use of data obtained from the Chandra Data Archive and software provided by the Chandra X-ray Center (CXC) in the application packages CIAO and Sherpa. We thank helpful discussions with F. Pacucci, A. Ricarte and P. Edmonds. Á.B., G.R.T., R.P.K., C.J. and W.R.F. acknowledge support from the Smithsonian Institution and the CXC through NASA contract NAS8-03060. A.D.G. acknowledges support from NSF/AAG grant no. 1007094. P.N. acknowledges support from the Black Hole Initiative at Harvard University, which is funded by grants from the John Templeton Foundation and the Gordon and Betty Moore Foundation. O.E.K. is supported by the GAČR EXPRO grant no. 21-13491X.

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Authors and Affiliations



Á.B. is the principal investigator of the Chandra proposal, analysed the Chandra observations, led the analysis and drafted the paper. A.D.G. and P.N. contributed equally. A.D.G. carried out the spectral fitting of the X-ray source, played a major role in writing the paper and provided a figure. P.N. led the theoretical interpretation and played a major role in writing the paper. O.E.K. contributed to the analysis of the Chandra data and its interpretation and provided a figure. G.R.T. contributed figures and text to the paper. U.C. contributed to the sample selection and data analysis. M.V. contributed to the interpretation and text of the paper. R.P.K. contributed to the interpretation of the paper. W.R.F., C.J., E.C. and I.Z. reviewed the paper and contributed to the text.

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Correspondence to Ákos Bogdán.

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Bogdán, Á., Goulding, A.D., Natarajan, P. et al. Evidence for heavy-seed origin of early supermassive black holes from a z ≈ 10 X-ray quasar. Nat Astron (2023).

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