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# Turbulent cold flows gave birth to the first quasars

## Abstract

How quasars powered by supermassive black holes formed less than a billion years after the Big Bang is still one of the outstanding problems in astrophysics, 20 years after their discovery1,2,3,4. Cosmological simulations suggest that rare cold flows converging on primordial haloes in low-shear environments could have created these quasars if they were 104–105 solar masses at birth, but could not resolve their formation5,6,7,8. Semi-analytical studies of the progenitor halo of a primordial quasar found that it favours the formation of such seeds, but could not verify if one actually appeared9. Here we show that a halo at the rare convergence of strong, cold accretion flows creates massive black holes seeds without the need for ultraviolet backgrounds, supersonic streaming motions or even atomic cooling. Cold flows drive violent, supersonic turbulence in the halo, which prevents star formation until it reaches a mass that triggers sudden, catastrophic baryon collapse that forms 31,000 and 40,000 solar-mass stars. This simple, robust process ensures that haloes capable of forming quasars by a redshift of z > 6 produce massive seeds. The first quasars were thus a natural consequence of structure formation in cold dark matter cosmologies, and not exotic, finely tuned environments as previously thought10,11,12,13,14.

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## Data availability

The Enzo parameter files and initial conditions files generated by MUSIC that are required to perform the simulations are available at https://doi.org/10.5281/zenodo.5853118. The MUSIC input files required to generate the initial conditions are available at https://sites.google.com/site/latifmaastro/ics. The MESA inlist files required to evolve the two stars can be found at https://cococubed.com/mesa_market/inlists.html.

## Code availability

The code used to produce our cosmological simulations, Enzo v.2.6, can be found at https://bitbucket.org/enzo/enzo-dev/tree/enzo-2.6.1. The MESA code used to evolve the two stars, v.12778, can be found at https://zenodo.org/record/3698354#.YgkaN-TfUlQ.

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## Acknowledgements

M.A.L. was supported by UAEU UPAR grant no. 31S390. S.K. acknowledges support from the UK STFC via grant ST/V000594/1. N.P.H. acknowledges funding from the European Research Council for the Horizon 2020 ERC Consolidator Grant project ICYBOB, grant no. 818940. T.E.W. acknowledges support from the NRC-Canada Plaskett Fellowship. The Enzo simulations were performed on HPC resources at UAEU and the Institute of Cosmology and Gravitation at the University of Portsmouth (Sciama). D.J.W. was supported by the Ida Pfeiffer Professorship at the Institute of Astrophysics at the University of Vienna.

## Author information

Authors

### Contributions

D.J.W. proposed this study, assisted in its development and wrote the paper. M.A.L. developed this study, performed the Enzo simulations and analysed its data. S.K. contributed to the development of this study and the interpretation of its results. N.P.H. performed the MESA calculations and analysed its results with T.E.W.

### Corresponding authors

Correspondence to M. A. Latif or D. J. Whalen.

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### Competing interests

The authors declare no competing interests.

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## Extended data figures and tables

### Extended Data Fig. 1 Additional radial gas profiles at collapse.

The ratio of the enclosed gas mass to the Jeans mass (a) and gas infall rates (b) are at the onset of collapse (green), 5 kyr (blue), and at 11 kyr (red). Regions where the ratio exceeds 1 are where gas is prone to collapse. H2 mass fractions (c) are at the same times. At 11 kyr they approach unity at the smallest scales, indicating the nearly complete molecularization of the core.

### Extended Data Fig. 2 C1 and C2 masses vs. time in the pressure floor run (solid) and the sink particle run (dashed).

The occasional slight dips in C1 mass are due to tidal stripping with other structures in the core.

### Extended Data Fig. 3 Evolution of SMS 1 and SMS 2.

Accretion rates are shown in (a) and Hertzsprung-Russell tracks are shown in (b).

### Extended Data Fig. 4 Halo mass vs. redshift.

The masses in (a) are from z = 35 (80 Myr after the Big Bang), when it crosses the threshold for normal Pop III star formation, to z = 25.7 (126 Myr after the Big Bang), when it begins to dynamically collapse. The subsequent growth of the halo from z = 15 to z = 6 is shown in (b).

### Extended Data Fig. 5 Structure of the turbulent core in the sink particle run.

Images are 25 pc on a side and the times in a and b are 0.6 Myr and 1.0 Myr after collapse, respectively.

### Extended Data Fig. 6 Kippenhahn diagrams for the two stars.

Internal structures for SMS 1 and 2 are shown in (a) and (b), respectively. The x- and y-axes are time and mass coordinate, respectively, so the interior structure of the star and energy generation at a given time can be read from the vertical line through the diagram at that time. Colours show energy generation rates, $${\varepsilon }_{{\rm{nuc}}}$$, at each mass coordinate and red contours mark regions where convection dominates energy transport (all other regions are radiative).

### Extended Data Fig. 7 The collapse of SMS 1 and SMS 2 to DCBHs.

Infall velocities are shown vs. mass coordinate in (a) and vs. radius in (b).

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Latif, M.A., Whalen, D.J., Khochfar, S. et al. Turbulent cold flows gave birth to the first quasars. Nature 607, 48–51 (2022). https://doi.org/10.1038/s41586-022-04813-y

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• DOI: https://doi.org/10.1038/s41586-022-04813-y