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Black hole growth in the early Universe is self-regulated and largely hidden from view


A Corrigendum to this article was published on 08 June 2017


The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies1,2,3. Although some black holes with masses more than 109 times that of the Sun have been detected in luminous quasars less than one billion years after the Big Bang4,5, these individual extreme objects have limited utility in constraining the channels of formation of the earliest black holes; this is because the initial conditions of black hole seed properties are quickly erased during the growth process6. Here we report a measurement of the amount of black hole growth in galaxies at redshift z = 6–8 (0.95–0.7 billion years after the Big Bang), based on optimally stacked, archival X-ray observations. Our results imply that black holes grow in tandem with their host galaxies throughout cosmic history, starting from the earliest times. We find that most copiously accreting black holes at these epochs are buried in significant amounts of gas and dust that absorb most radiation except for the highest-energy X-rays. This suggests that black holes grew significantly more during these early bursts than was previously thought, but because of the obscuration of their ultraviolet emission they did not contribute to the re-ionization of the Universe.

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Figure 1: Accreted black hole mass density as a function of redshift.
Figure 2: Cumulative number of sources as a function of redshift for individual X-ray detections.


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We thank T. Goto, M. Urry and D. Sanders for conversations. Support for the work of E.T. and K.S. was provided by NASA through Chandra/Einstein Post-doctoral Fellowship Awards. M.V. acknowledges support from the Smithsonian Astrophysical Observatory. P.N. acknowledges support via a Guggenheim Fellowship from the John Simon Guggenheim Foundation. The work of E.G. was partially funded by the NSF.

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Authors and Affiliations



E.T. started the project, collected the galaxy samples, performed the X-ray stacking calculations and wrote the majority of the text. K.S. helped to collect the galaxy sample studied here, and contributed to the conception of the project and the analysis and interpretation of the results. M.V. and P.N. created the black hole growth models, computed the contribution of these sources to the re-ionization of the Universe and contributed extensively to the theoretical interpretation of the observational results. E.G. developed the optimal X-ray stacking formalism and worked with E.T. to implement it on these data. All authors discussed the results and contributed to the writing of the manuscript.

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Correspondence to Ezequiel Treister.

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The authors declare no competing financial interests.

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Treister, E., Schawinski, K., Volonteri, M. et al. Black hole growth in the early Universe is self-regulated and largely hidden from view. Nature 474, 356–358 (2011).

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