Jarrett L. Johnson, Daniel J. Whalen, Hui Li, Daniel E. Holz
Recent observations of quasars powered by supermassive black holes (SMBHs) out to z > 7 allow to constrain both the initial seed masses and the growth of the most massive black holes (BHs) in the early universe. The combination of the limited role of mergers in growing seed BHs as inferred from recent cosmological simulations, the sub-Eddington accretion rates of BHs expected at the earliest times, and the large radiative efficiencies of the most massive BHs inferred from observations of active galactic nuclei at high redshift, all suggest that the initial BH seeds may have been as massive as > 10^5 solar masses. This is 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 10^4 --10^6 solar mass seed BH. This also corroborates the results of recent cosmological simulations which suggest that these massive BHs were the seeds of a large fraction of the SMBHs residing in the centers of galaxies today.
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http://arxiv.org/abs/1211.0548
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