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The growth of light seed black holes in the early Universe

Nature Astronomy (2026)Cite this article

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Abstract

Observations by the James Webb Space Telescope have uncovered supermassive black holes with masses exceeding 106 M⊙ at redshifts z > 8, posing serious challenges to existing models of early black hole formation and growth. Here we show, in a fully cosmological setting, that light seed black holes, remnants of population III stars, can grow rapidly to ~104 M⊙ in the early Universe. This growth is enabled by our new black hole seeding prescription and the unprecedented resolution of our zoom-in cosmological simulations, which resolve the dense environments necessary for efficient accretion. Our results provide robust evidence that light seed black holes can attain the masses required to serve as the dominant progenitors of the population of supermassive black holes observed at later cosmic epochs. These findings have far-reaching implications for the interpretation of observations by the James Webb Space Telescope and future gravitational wave detections with LISA.

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Fig. 1: Mass growth history of BHs.
Fig. 2: Gas density projection for PopIII star formation, BH formation, supernova feedback and thermal feedback for the most massive BH in the L15_BHFB simulation.
Fig. 3: BH growth in terms of the Eddington fraction.
Fig. 4: Gas properties within 10 pc of growing BHs.

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Data availability

The simulation outputs generated and analysed in this study amount to approximately 6 TB and cannot be hosted in a public repository due to their size. These data are available from the corresponding author upon reasonable request, and we will provide the full set of snapshots and derived data products necessary to reproduce the analyses presented in the paper. Summary products required for figure generation (BH growth histories, gas properties, halo catalogues and extracted time series) are available via figshare at https://doi.org/10.6084/m9.figshare.30857603 (ref. 79). Source data are available with this paper.

Code availability

The simulations were carried out with a proprietary version of the publicly available Arepo code. The publicly released version of Arepo can be obtained from the Max Planck Institute for Astrophysics (https://arepo-code.org). The modified, proprietary version used for our production runs cannot be redistributed. All analysis scripts developed for this study—including routines for processing the snapshots, computing derived quantities, and generating the figures—are available via Zenodo at https://doi.org/10.5281/zenodo.17894541 (ref. 80).

References

  1. Madau, P. & Rees, M. J. Massive black holes as population III remnants. Astrophys. J. Lett. 551, L27–L30 (2001).

    Article  ADS  Google Scholar 

  2. Volonteri, M., Haardt, F. & Madau, P. The assembly and merging history of supermassive black holes in hierarchical models of galaxy formation. Astrophys. J. 582, 559–573 (2003).

    Article  ADS  Google Scholar 

  3. Madau, P., Rees, M. J., Volonteri, M., Haardt, F. & Oh, S. P. Early reionization by miniquasars. Astrophys. J. 604, 484–494 (2004).

    Article  ADS  Google Scholar 

  4. Volonteri, M. The formation and evolution of massive black holes. Science 337, 544 (2012).

    Article  ADS  Google Scholar 

  5. Latif, M. A., Whalen, D. & Khochfar, S. The birth mass function of population III stars. Astrophys. J. 925, 28 (2022).

    Article  ADS  Google Scholar 

  6. Abel, T., Bryan, G. L. & Norman, M. L. The formation of the first star in the Universe. Science 295, 93–98 (2002).

    Article  ADS  Google Scholar 

  7. Bromm, V., Coppi, P. S. & Larson, R. B. The formation of the first stars. I. The primordial star-forming cloud. Astrophys. J. 564, 23–51 (2002).

    Article  ADS  Google Scholar 

  8. O’Shea, B. W. & Norman, M. L. Population III star formation in a ΛCDM Universe. II. Effects of a photodissociating background. Astrophys. J. 673, 14–33 (2008).

    Article  ADS  Google Scholar 

  9. Turk, M. J., Abel, T. & O’Shea, B. The formation of population III binaries from cosmological initial conditions. Science 325, 601 (2009).

    Article  ADS  Google Scholar 

  10. Hirano, S. et al. One hundred first stars: protostellar evolution and the final masses. Astrophys. J. 781, 60 (2014).

    Article  ADS  Google Scholar 

  11. Prole, L. R. et al. From dark matter halos to pre-stellar cores: high resolution follow-up of cosmological Lyman-Werner simulations. Mon. Not. R. Astron. Soc. 520, 2081–2093 (2023).

    Article  ADS  Google Scholar 

  12. Woosley, S. E. & Weaver, T. A. The evolution and explosion of massive stars. II. Explosive hydrodynamics and nucleosynthesis. Astrophys. J. Suppl. Ser. 101, 181 (1995).

    Article  ADS  Google Scholar 

  13. Nomoto, K., Tominaga, N., Umeda, H., Kobayashi, C. & Maeda, K. Nucleosynthesis yields of core-collapse supernovae and hypernovae, and galactic chemical evolution. Nucl. Phys. A 777, 424–458 (2006).

    Article  ADS  Google Scholar 

  14. Heger, A. & Woosley, S. E. The nucleosynthetic signature of population III. Astrophys. J. 567, 532–543 (2002).

    Article  ADS  Google Scholar 

  15. Lupi, A. et al. Growing massive black holes through supercritical accretion of stellar-mass seeds. Mon. Not. R. Astron. Soc. 456, 2993–3003 (2016).

    Article  ADS  Google Scholar 

  16. Smith, B. D. et al. The growth of black holes from population III remnants in the Renaissance simulations. Mon. Not. R. Astron. Soc. 480, 3762–3773 (2018).

    Article  ADS  Google Scholar 

  17. Regan, J. A. et al. Super-Eddington accretion and feedback from the first massive seed black holes. Mon. Not. R. Astron. Soc. 486, 3892–3906 (2019).

    Article  ADS  Google Scholar 

  18. Sassano, F., Capelo, P. R., Mayer, L., Schneider, R. & Valiante, R. Super-critical accretion of medium-weight seed black holes in gaseous proto-galactic nuclei. Mon. Not. R. Astron. Soc. 519, 1837–1855 (2023).

    Article  ADS  Google Scholar 

  19. Inayoshi, K., Haiman, Z. & Ostriker, J. P. Hyper-Eddington accretion flows on to massive black holes. Mon. Not. R. Astron. Soc. 459, 3738–3755 (2016).

    Article  ADS  Google Scholar 

  20. Jiang, Y.-F., Stone, J. M. & Davis, S. W. Super-Eddington accretion disks around supermassive black holes. Astrophys. J. 880, 67 (2019).

    Article  ADS  Google Scholar 

  21. Park, K., Wise, J. H., Bogdanovic, T. & Ricotti, M. Biconical-dominated accretion flow onto seed black holes in a hyperaccretion regime. Astrophys. J. 905, 92 (2020).

    Article  ADS  Google Scholar 

  22. Kitaki, T., Mineshige, S., Ohsuga, K. & Kawashima, T. The origins and impact of outflow from super-Eddington flow. Publ. Astron. Soc. Jpn 73, 450–466 (2021).

    Article  ADS  Google Scholar 

  23. Botella, I., Mineshige, S., Kitaki, T., Ohsuga, K. & Kawashima, T. Structure of the super-Eddington outflow and its impact on the cosmological scale. Publ. Astron. Soc. Jpn 74, 384–397 (2022).

    Article  ADS  Google Scholar 

  24. Lambrides, E. et al. The case for super-Eddington accretion: connecting weak X-ray and UV line emission in JWST broad-line AGN during the first Gyr of cosmic time. Preprint at https://arxiv.org/abs/2409.13047 (2024).

  25. Suh, H. et al. A super-Eddington-accreting black hole ~1.5 Gyr after the Big Bang observed with JWST. Nat. Astron. 9, 271–279 (2025).

    Article  ADS  Google Scholar 

  26. Shi, Y., Kremer, K., Grudic, M. Y., Gerling-Dunsmore, H. J. & Hopkins, P. F. Hyper-Eddington black hole growth in star-forming molecular clouds and galactic nuclei: can it happen? Mon. Not. R. Astron. Soc. 518, 3606–3621 (2023).

    Article  ADS  Google Scholar 

  27. Gordon, S. T., Smith, B. D., Khochfar, S. & Regan, J. A. Hungry or not: how stellar-mass black holes grow (or don’t) in dark matter mini-haloes at high resolution. Mon. Not. R. Astron. Soc. 529, 604–627 (2024).

    Article  ADS  Google Scholar 

  28. Mehta, D., Regan, J. A. & Prole, L. Growth of light-seed black holes in gas-rich galaxies at high redshift. Open J. Astrophys. 7, 107 (2024).

    Article  ADS  Google Scholar 

  29. Alexander, T. & Natarajan, P. Rapid growth of seed black holes in the early Universe by supra-exponential accretion. Science 345, 1330–1333 (2014).

    Article  ADS  Google Scholar 

  30. Zana, T. et al. Super-Eddington accretion in protogalactic cores. Preprint at https://arxiv.org/abs/2508.21114 (2025).

  31. Alvarez, M. A., Wise, J. H. & Abel, T. Accretion onto the first stellar-mass black holes. Astrophys. J. Lett. 701, L133–L137 (2009).

    Article  ADS  Google Scholar 

  32. Springel, V. E pur si muove: Galilean-invariant cosmological hydrodynamical simulations on a moving mesh. Mon. Not. R. Astron. Soc. 401, 791–851 (2010).

    Article  ADS  Google Scholar 

  33. Pakmor, R. et al. Improving the convergence properties of the moving-mesh code AREPO. Mon. Not. R. Astron. Soc. 455, 1134–1143 (2016).

    Article  ADS  Google Scholar 

  34. Hahn, O. & Abel, T. Multi-scale initial conditions for cosmological simulations. Mon. Not. R. Astron. Soc. 415, 2101–2121 (2011).

    Article  ADS  Google Scholar 

  35. Prole, L. R., Regan, J. A., Mehta, D., Coles, P. & Dayal, P. Primordial black holes in cosmological simulations: growth prospects for supermassive black holes. Open J. Astrophys. 8, 126 (2025).

    Article  ADS  Google Scholar 

  36. Prole, L. R. et al. The SEEDZ simulations: methodology and first results on massive black hole seeding and early galaxy growth. Preprint at https://arxiv.org/abs/2511.09640 (2025).

  37. Qin, Y., Mesinger, A., Park, J., Greig, B. & Munoz, J. B. A tale of two sites. I. Inferring the properties of minihalo-hosted galaxies from current observations. Mon. Not. R. Astron. Soc. 495, 123–140 (2020).

    Article  ADS  Google Scholar 

  38. Shi, Y., Kremer, K. & Hopkins, P. F. Feedback-regulated seed black hole growth in star-forming molecular clouds and galactic nuclei. Astron. Astrophys. 691, A24 (2024).

    Article  ADS  Google Scholar 

  39. Gordon, S. T., Smith, B. D., Khochfar, S. & Beckmann, R. S. Conditions for super-Eddington accretion onto the first black holes. Mon. Not. R. Astron. Soc. 537, 674–690 (2025).

    Article  ADS  Google Scholar 

  40. Regan, J. A. et al. The formation of very massive stars in early galaxies and implications for intermediate mass black holes. Open J. Astrophys. 3, 15 (2020).

    Article  ADS  Google Scholar 

  41. Jaura, O. et al. Trapping of H II regions in population III star formation. Mon. Not. R. Astron. Soc. 512, 116–136 (2022).

    Article  ADS  Google Scholar 

  42. Volonteri, M., Silk, J. & Dubus, G. The case for supercritical accretion onto massive black holes at high redshift. Astrophys. J. 804, 148 (2015).

    Article  ADS  Google Scholar 

  43. Jiang, Y.-F., Stone, J. M. & Davis, S. W. A global three-dimensional radiation magneto-hydrodynamic simulation of super-Eddington accretion disks. Astrophys. J. 796, 106 (2014).

    Article  ADS  Google Scholar 

  44. Tremmel, M., Governato, F., Volonteri, M. & Quinn, T. R. Off the beaten path: a new approach to realistically model the orbital decay of supermassive black holes in galaxy formation simulations. Mon. Not. R. Astron. Soc. 451, 1868–1874 (2015).

    Article  ADS  Google Scholar 

  45. Pfister, H., Volonteri, M., Dubois, Y., Dotti, M. & Colpi, M. The erratic dynamical life of black hole seeds in high-redshift galaxies. Mon. Not. R. Astron. Soc. 486, 101–111 (2019).

    Article  ADS  Google Scholar 

  46. Taylor, P. & Kobayashi, C. Seeding black holes in cosmological simulations. Mon. Not. R. Astron. Soc. 442, 2751–2767 (2014).

    Article  ADS  Google Scholar 

  47. Habouzit, M., Volonteri, M. & Dubois, Y. Blossoms from black hole seeds: properties and early growth regulated by supernova feedback. Mon. Not. R. Astron. Soc. 468, 3935–3948 (2017).

    Article  ADS  Google Scholar 

  48. Bhowmick, A. K. et al. Introducing the BRAHMA simulation suite: signatures of low-mass black hole seeding models in cosmological simulations. Mon. Not. R. Astron. Soc. 531, 4311–4335 (2024).

    Article  ADS  Google Scholar 

  49. Pérez-González, P. G. et al. What Is the nature of little red dots and what is not, MIRI SMILES Edition. Astrophys. J. 968, 4 (2024).

    Article  ADS  Google Scholar 

  50. Kokorev, V. et al. A census of photometrically selected little red dots at 4 < z < 9 in JWST blank fields. Astrophys. J. 968, 38 (2024).

    Article  ADS  Google Scholar 

  51. Springel, V., Pakmor, R., Zier, O. & Reinecke, M. Simulating cosmic structure formation with the GADGET-4 code. Mon. Not. R. Astron. Soc. 506, 2871–2949 (2021).

    Article  ADS  Google Scholar 

  52. Bourne, M. A., Fiacconi, D., Sijacki, D., Piotrowska, J. M. & Koudmani, S. Dynamics and spin alignment in massive, gravito-turbulent circumbinary discs around supermassive black hole binaries. Mon. Not. R. Astron. Soc. 534, 3448–3477 (2024).

    Article  ADS  Google Scholar 

  53. Planck Collaboration Planck 2018 results. VI. Cosmological parameters. Astron. Astrophys. 641, A6 (2020).

    Article  Google Scholar 

  54. Wollenberg, K. M. J., Glover, S. C. O., Clark, P. C. & Klessen, R. S. Formation sites of population III star formation: effects of rotation and turbulence on fragmentation. Mon. Not. R. Astron. Soc. 494, 1871–1893 (2020).

    Article  ADS  Google Scholar 

  55. Tress, R. G. et al. Simulations of the Milky Way’s central molecular zone. I. Gas dynamics. Mon. Not. R. Astron. Soc. 499, 4455–4478 (2020).

    Article  ADS  Google Scholar 

  56. Krumholz, M. R., McKee, C. F. & Klein, R. I. Embedding Lagrangian sink particles in Eulerian grids. Astrophys. J. 611, 399–412 (2004).

    Article  ADS  Google Scholar 

  57. Bryan, G. L. et al. ENZO: an adaptive mesh refinement code for astrophysics. Astrophys. J. Suppl. Ser. 211, 19 (2014).

    Article  ADS  Google Scholar 

  58. Regan, J. A. & Downes, T. P. Rise of the first supermassive stars. Mon. Not. R. Astron. Soc. 478, 5037–5049 (2018).

    Article  ADS  Google Scholar 

  59. Brummel-Smith, C. et al. ENZO: an adaptive mesh refinement code for astrophysics (version 2.6). J. Open Source Softw. 4, 1636 (2019).

    Article  ADS  Google Scholar 

  60. Truelove, J. et al. The Jeans condition: a new constraint on spatial resolution in simulations of isothermal self-gravitational hydrodynamics. Astrophys. J. 489, L179 (1997).

    Article  ADS  Google Scholar 

  61. Maeder, A. Physics, Formation and Evolution of Rotating Stars (Springer, 2009).

  62. Gatto, A. et al. Modelling the supernova-driven ISM in different environments. Mon. Not. R. Astron. Soc. 449, 1057–1075 (2015).

    Article  ADS  Google Scholar 

  63. Magg, M. et al. Metal mixing in minihalos: the descendants of pair-instability supernovae. Astrophys. J. 929, 119 (2022).

    Article  ADS  Google Scholar 

  64. Smith, M. C., Sijacki, D. & Shen, S. Cosmological simulations of dwarfs: the need for ISM physics beyond SN feedback alone. Mon. Not. R. Astron. Soc. 485, 3317–3333 (2019).

    Article  ADS  Google Scholar 

  65. Bondi, H. On spherically symmetrical accretion. Mon. Not. R. Astron. Soc. 112, 195 (1952).

    Article  ADS  MathSciNet  Google Scholar 

  66. Krumholz, M. R., McKee, C. F. & Klein, R. I. Bondi–Hoyle accretion in a turbulent medium. Astrophys. J. 638, 369–381 (2006).

    Article  ADS  Google Scholar 

  67. Di Matteo, T., Springel, V. & Hernquist, L. Energy input from quasars regulates the growth and activity of black holes and their host galaxies. Nature 433, 604–607 (2005).

    Article  ADS  Google Scholar 

  68. Springel, V., Di Matteo, T. & Hernquist, L. Modelling feedback from stars and black holes in galaxy mergers. Mon. Not. R. Astron. Soc. 361, 776–794 (2005).

    Article  ADS  Google Scholar 

  69. Sijacki, D., Springel, V., Di Matteo, T. & Hernquist, L. A unified model for AGN feedback in cosmological simulations of structure formation. Mon. Not. R. Astron. Soc. 380, 877–900 (2007).

    Article  ADS  Google Scholar 

  70. Di Matteo, T., Colberg, J., Springel, V., Hernquist, L. & Sijacki, D. Direct cosmological simulations of the growth of black holes and galaxies. Astrophys. J. 676, 33–53 (2008).

    Article  ADS  Google Scholar 

  71. Sadowski, A., Lasota, J.-P., Abramowicz, M. A. & Narayan, R. Energy flows in thick accretion discs and their consequences for black hole feedback. Mon. Not. R. Astron. Soc. 456, 3915–3928 (2016).

    Article  ADS  Google Scholar 

  72. Abramowicz, M. A. & Fragile, P. C. Foundations of black hole accretion disk theory. Living Rev. Relativ. 16, 1 (2013).

    Article  ADS  Google Scholar 

  73. Madau, P., Haardt, F. & Dotti, M. Super-critical growth of massive black holes from stellar-mass seeds. Astrophys. J. Lett. 784, L38 (2014).

    Article  ADS  Google Scholar 

  74. Dalla Vecchia, C. & Schaye, J. Simulating galactic outflows with thermal supernova feedback. Mon. Not. R. Astron. Soc. 426, 140–158 (2012).

    Article  ADS  Google Scholar 

  75. Prole, L. R., Clark, P. C., Klessen, R. S. & Glover, S. C. O. Fragmentation-induced starvation in population III star formation: a resolution study. Mon. Not. R. Astron. Soc. 510, 4019–4030 (2022).

    Article  ADS  Google Scholar 

  76. Hartwig, T., Glover, S. C. O., Klessen, R. S., Latif, M. A. & Volonteri, M. How an improved implementation of H2 self-shielding influences the formation of massive stars and black holes. Mon. Not. R. Astron. Soc. 452, 1233–1244 (2015).

    Article  ADS  Google Scholar 

  77. Clark, P. C. et al. The formation and fragmentation of disks around primordial protostars. Science 331, 1040 (2011).

    Article  ADS  Google Scholar 

  78. Schauer, A. T. P., Regan, J., Glover, S. C. O. & Klessen, R. S. The formation of direct collapse black holes under the influence of streaming velocities. Mon. Not. R. Astron. Soc. 471, 4878–4884 (2017).

    Article  ADS  Google Scholar 

  79. Mehta, D. H., Regan, J. A. & Prole, L. Analysis datasets for Mehta et al. 202X. figshare https://doi.org/10.6084/m9.figshare.30857603 (2025).

  80. Mehta, D. H., Regan, J. A. & Prole, L. Analysis pipeline for Mehta et al. 202X. Zenodo https://doi.org/10.5281/zenodo.17894541 (2025).

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Acknowledgements

J.A.R. acknowledges support from the Royal Society and Research Ireland (Grant No. URF/R1/191132). D.H.M., J.A.R. and L.P. acknowledge support from the Research Ireland Laureate programme (Grant No. IRCLA/2022/1165). The simulations were performed on the Czech Republic EuroHPC machine Karolina hosted by IT4Innovations through a EuroHPC Regular Access call (EHPC-REG-2023R03-103, EHPC-REG-2025R01-008) and on the Luxembourg machine Meluxina. We acknowledge the Irish Centre for High-End Computing for the provision of computational facilities and support.

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Authors and Affiliations

  1. Department of Physics, Maynooth University, Maynooth, Ireland

    Daxal H. Mehta, John A. Regan & Lewis Prole

  2. Centre for Astrophysics and Space Science, Maynooth University, Maynooth, Ireland

    Daxal H. Mehta, John A. Regan & Lewis Prole

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  1. Daxal H. Mehta
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Contributions

D.H.M., J.A.R. and L.P. conceived the idea for the project. D.H.M. performed the simulation and analysis and drafted the paper. J.A.R. performed the coarse 40-Mpc simulations. All authors contributed to the interpretation of the results and to the text of the final paper.

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Correspondence to Daxal H. Mehta.

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Extended data

Extended Data Fig. 1 Population density of PopIII stars.

We show the IMF of PopIII stars from all our simulations. The simulations L13, L14, L15 and L15_BHFB are coloured red, blue, violet and yellow respectively. This is the top-heavy IMF with a characteristic mass of 20 M⊙. The minimum mass of PopIII stars in 1 and the maximum mass is 300 M⊙.

Source data

Extended Data Fig. 2 Mass function of halos and galaxies.

We show the number of halos (dashed lines) identified through the FOF algorithm across each of our simulations. The simulations L13, L14, L15 and L15_BHFB are coloured red, blue, violet and yellow respectively. We also highlight the number of galaxies (solid lines) within the halos that went on to have star formation and host BHs. We do not count here halos with mass 105 M⊙. We find that with increasing resolution, star formation begins in smaller and smaller galaxies.

Source data

Extended Data Fig. 3 Final mass of BHs vs initial mass of their PopIII progenitor stars.

We show the final masses of BHs as a function of their progenitor PopIII stars. All black dots are BHs that grew larger than their progenitor mass while red dots are BHs that did not accrete any gas. The shaded patch in yellow denotes the BH formed after undergoing a Type-II supernova. The shaded purple patch is for PISN, so there are no BH remnants. While in the white patch are BHs formed through the direct collapse channel. Interestingly, all of the BHs that grow formed through the direct collapse channel.

Source data

Extended Data Fig. 4 Gas temperature projection for PopIII star formation, supernova feedback, and BH feedback for the most massive BH in the L15_BHFB simulations.

a, b, c: Gas collapses to form cold galaxies in hot cosmic filaments. Within these galaxies, PopIII star formation occurs. d: The first PopIII star transitions to a BH and accretes the surrounding mass, simultaneously injecting thermal energy back into the gas. This thermal energy causes the galaxy to be distorted. e: The galaxy eventually reassembles triggering a second epoch of star formation. f: SNe from PopIII stars and BH thermal feedback heats up the gas to 105 K, which halts further BH growth and star formation.

Source data

Extended Data Fig. 5 BH particle growth plots.

We show the growth of BH particles with time after they transition from PopIII particles for BHs that accreted more than 0.1 M⊙ (dashed) and BHs that doubled their initial mass (solid lines). The simulations L13, L14, L15 and L15_BHFB are coloured red, blue, violet and yellow respectively. On average, we the find the growth phase lasting around a million years. We also see a trend that with increasing resolution, the timescales shorten.

Source data

Extended Data Fig. 6 Average metallicity of gas surrounding the BHs.

We show the average metallicity of gas surrounding the BHs during its entire growth phase. The simulations L13, L14, L15 and L15_BHFB are coloured red, blue, violet and yellow respectively. In our simulations, we have a metallicity floor of 10−10 Z⊙. We have a subset of BHs growing in pristine metal-free conditions, but we also see growth of BHs in galaxies enriched with metals.

Source data

Extended Data Fig. 7 Relation between BH growth and halo properties.

a: We show the final masses of BHs (Mf) as a function of its host halo mass. The simulations L13, L14, L15 and L15_BHFB are coloured red, blue, violet and yellow respectively. The dots show BHs that accreted more than 0.1 M⊙ and crosses focus on BHs that accreted more than their initial mass (Mi). We see no correlation between the two, suggesting that the halo does not need to be special in order for BHs to grow. b: We see a similar result when comparing the final masses with surface density of gas surrounding the BHs. However, we are incomplete in sampling larger halo masses and it is possible, even likely, that more massive halos would support additional growth and will also likely support the growth of LSBHs which have already experienced previous growth episodes.

Source data

Extended Data Fig. 8 Impact of radiation pressure on BH Growth.

We show the fraction of inward gas momentum against the outward radiation pressure flux for all BHs that accreted more than a thousand M⊙. Similar to our feedback simulation L15_BHFB, we find growth possible for a small subset of LSBHs.

Source data

Extended Data Fig. 9 Number density of MBHs and galaxies in our simulations.

We show the number density evolution of BHs above 1000 M⊙ (solid lines) along with the galaxy (dashed lines) number density. The simulations L13, L14, L15 and L15_BHFB are coloured red, blue, violet and yellow respectively. The plot highlights one of our results, that increasing resolution helps us capture LSBH growth. The number density of BHs reaches almost 100 cMpc−3 for the L15 simulation. In the L15_BHFB simulation, the number density decreases to below 20 cMpc−3, which is still much larger than the number density of the high-z AGN populations ≲ 10−2 cMpc−3, making LSBHs promising progenitors for SMBHs.

Source data

Source data

Source Data Fig. 1

Statistical source data (also uploaded to a separate repository 10.5281/zenodo.17899001).

Source Data Fig. 2

Statistical source data (also uploaded to a separate repository 10.5281/zenodo.17899001).

Source Data Fig. 3

Statistical source data.

Source Data Fig. 4

Statistical source data.

Source Data Extended Data Fig. 1

Statistical source data.

Source Data Extended Data Fig. 2

Statistical source data.

Source Data Extended Data Fig. 3

Statistical source data.

Source Data Extended Data Fig. 4

Statistical source data (also uploaded to a separate repository 10.5281/zenodo.17899001).

Source Data Extended Data Fig. 5

Statistical source data (also uploaded to a separate repository 10.5281/zenodo.17899001).

Source Data Extended Data Fig. 6

Statistical source data.

Source Data Extended Data Fig. 7

Statistical source data.

Source Data Extended Data Fig. 8

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Source Data Extended Data Fig. 9

Statistical source data.

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Mehta, D.H., Regan, J.A. & Prole, L. The growth of light seed black holes in the early Universe. Nat Astron (2026). https://doi.org/10.1038/s41550-025-02767-5

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