SUPERMASSIVE SEEDS FOR SUPERMASSIVE BLACK HOLES
- Nuclear and Particle Physics, Astrophysics and Cosmology Group (T-2), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
Recent observations of quasars powered by supermassive black holes (SMBHs) out to z {approx}> 7 constrain both the initial seed masses and the growth of the most massive black holes (BHs) in the early universe. Here we elucidate the implications of the radiative feedback from early generations of stars and from BH accretion for popular models for the formation and growth of seed BHs. We show that by properly accounting for (1) the limited role of mergers in growing seed BHs as inferred from cosmological simulations of early star formation and radiative feedback, (2) the sub-Eddington accretion rates of BHs expected at the earliest times, and (3) the large radiative efficiencies {epsilon} of the most massive BHs inferred from observations of active galactic nuclei at high redshift ({epsilon} {approx}> 0.1), we are led to the conclusion that the initial BH seeds may have been as massive as {approx}> 10{sup 5} M{sub Sun }. This presents a strong challenge to the Population III seed model, which calls for seed masses of {approx}100 M{sub Sun} and, even with constant Eddington-limited accretion, requires {epsilon} {approx}< 0.09 to explain the highest-z SMBHs in today's standard {Lambda}CDM cosmological model. It is, however, consistent with the prediction of the direct collapse scenario of SMBH seed formation, in which a supermassive primordial star forms in a region of the universe with a high molecule-dissociating background radiation field, and collapses directly into a 10{sup 4}-10{sup 6} M{sub Sun} seed BH. These results corroborate recent cosmological simulations and observational campaigns which suggest that these massive BHs were the seeds of a large fraction of the SMBHs residing in the centers of galaxies today.
- OSTI ID:
- 22140144
- Journal Information:
- Astrophysical Journal, Vol. 771, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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