It is noted that if a significant fraction of the mass in galaxies is contained in very massive black holes that formed before the galaxies, then any such objects passing through the interstellar gas of a galaxy should be highly luminous due to heating of accreted gas. Some observational questions associated with accreting pregalactic black holes in the Galaxy are considered. The question of whether accretion disks might be formed is analyzed, and it is found that both spherical and disk accretion should occur, with about 95% of the pregalactic black holes in the Galaxy probably undergoing essentially spherical accretion. Luminosities and characteristic wavelengths are computed for the cases of spherical and disk accretion. It is shown that spherical accretion is a highly efficient process for converting infalling mass-energy to outgoing radiation, and typical luminosities of 10 to the 37th power erg/s in the far-IR are predicted for spherical accretion. It is concluded that the pregalactic-black-hole hypothesis appears to be untenable because the luminosity that would be released by gas falling onto the holes as they traverse the galactic disk is incompatible with observations.
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Ipser et al. (1977) studied this question.