The Emergence of the First Star-free Atomic Cooling Haloes in the
  Universe
  Using the Renaissance suite of simulations we examine the emergence of
pristine atomic cooling haloes that are both metal-free and star-free in the
early Universe. The absence of metals prevents catastrophic cooling, suppresses
fragmentation, and may allow for the formation of massive black hole seeds.
Here we report on the abundance of pristine atomic cooling haloes found and on
the specific physical conditions that allow for the formation of these
direct-collapse-black-hole (DCBH) haloes. In total in our simulations we find
that 79 DCBH haloes form before a redshift of 11.6. We find that the formation
of pristine atomic haloes is driven by the rapid assembly of the atomic cooling
haloes with mergers, both minor and/or major, prior to reaching the atomic
cooling limit a requirement. However, the ability of assembling haloes to
remain free of (external) metal enrichment is equally important and underlines
the necessity of following the transport of metals in such simulations. The
candidate DCBH hosting haloes we find, have been exposed to mean Lyman-Werner
radiation fields of J$_{LW}$ $\sim$ 1 J$_{21}$ and typically lie at least 10
kpc (physical) from the nearest massive galaxy. Growth rates of the haloes
reach values of greater than 10$^7$ M$_{\odot}$ per unit redshift, leading to
significant dynamical heating and the suppression of efficient cooling until
the halo crosses the atomic cooling threshold. Finally, we also find five
synchronised halo candidates where pairs of pristine atomic cooling haloes
emerge that are both spatially and temporally synchronised.
