Black hole formation in the early universe
  Supermassive black holes with up to a $\rm 10^{9}~M_{\odot}$ dwell in the
centers of present-day galaxies, and their presence has been confirmed at z
$\geq$ 6. Their formation at such early epochs is still an enigma. Different
pathways have been suggested to assemble supermassive black holes in the first
billion years after the Big Bang. Direct collapse has emerged as a highly
plausible scenario to form black holes as it provides seed masses of $\rm
10^{5}-10^{6}~M_{\odot}$. Gravitational collapse in atomic cooling haloes with
virial temperatures T$_{vir} \geq 10^{4}$~K may lead to the formation of
massive seed black holes in the presence of an intense background UV flux.
Turbulence plays a central role in regulating accretion and transporting
angular momentum. We present here the highest resolution cosmological
large-eddy simulations to date which track the evolution of high-density
regions on scales of $0.25$~AU beyond the formation of the first peak, and
study the impact of subgrid-scale turbulence. The peak density reached in these
simulations is $\rm 1.2 \times 10^{-8}~g~cm^{-3}$. Our findings show that while
fragmentation occasionally occurs, it does not prevent the growth of a central
massive object resulting from turbulent accretion and occasional mergers. The
central object reaches $\rm \sim 1000~M_{\odot}$ within $4$ free-fall times,
and we expect further growth up to $\rm 10^{6}~M_{\odot}$ through accretion in
about 1 million years. The direct collapse model thus provides a viable pathway
of forming high-mass black holes at early cosmic times.
