The Growth of Black Holes from Population III Remnants in the
  Renaissance Simulations
  The formation of stellar mass black holes from the remnants of Population III
stars provides a source of initial black hole seeds with the potential to grow
into intermediate or, in rare cases, possibly supermassive black holes. We use
the Renaissance simulation suite to follow the growth of over 15,000 black
holes born into mini-haloes in the early Universe. We compute the evolution of
the black holes by post-processing individual remnant Population III star
particles in the Renaissance simulation snapshots. The black holes populate
haloes from 10$^{6}$ M$_{\odot}$ up to 10$^{9}$ M$_{\odot}$. We find that all
of the black holes display very inefficient growth. On average the black holes
increase their initial mass by a factor 10$^{-5}$, with the most active black
holes increasing their mass by approximately 10%. Only a single black hole
experiences any period of super-Eddington accretion, but the duration is very
short and not repeated. Furthermore, we find no correlation of black hole
accretion with halo mass in the mass range sampled. Within most haloes, we
identify clumps of cool, dense gas for which accretion rates would be high, but
instances of black holes encountering these clumps are rare and short-lived.
Star formation competes with black hole growth by consuming available gas and
driving down accretion rates through feedback. We conclude that the black holes
born from Population III remnants do not form a significant population of
intermediate mass black holes in the early Universe and will need to wait until
later times to undergo significant accretion, if at all.
