ACCRETION ONTO "SEED" BLACK HOLES IN THE FIRST GALAXIES

作者：Milosavljevic Milos^*; Bromm Volker; Couch Sean M; Oh S Peng

来源：Astrophysical Journal, 2009, 698(1): 766-780.

DOI：10.1088/0004-637X/698/1/766

• black hole physics
• cosmology: theory
• galaxies: active
• hydrodynamics
• quasars: general
• radiation mechanisms: general

The validity of the hypothesis that the massive black holes in high redshift quasars grew from stellar-sized "seeds" is contingent on a seed's ability to double its mass every few 10 million years. This requires that the seed accrete at approximately the Eddington-limited rate. In the specific case of radiatively efficient quasi-radial accretion in a metal-poor protogalactic medium, for which the Bondi accretion rate is often prescribed in cosmological simulations of massive black hole formation, we examine the effects of the radiation emitted near the black hole's event horizon on the structure of the surrounding gas flow. We find that photoheating and radiation pressure from photoionization significantly reduce the steady-state accretion rate and potentially render the quasi-radial accretion flow unsteady and inefficient. The time-averaged accretion rate is always a small fraction of the "Bondi" accretion rate calculated ignoring radiative feedback. The pressure of Ly alpha photons trapped near the H II region surrounding the black hole may further attenuate the inflow. These results suggest that an alternative to quasi-radial, radiatively efficient Bondi-like accretion should be sought to explain the rapid growth of quasar-progenitor seed black holes.

• 出版日期2009-6-10