  The origin of supermassive black holes (SMBHs) that inhabit the centers of
massive galaxies is largely unconstrained. Remnants from supermassive stars
(SMSs) with masses around 10,000 solar masses provide the ideal seed
candidates, known as direct collapse black holes. However, their very existence
and formation environment in the early Universe are still under debate, with
their supposed rarity further exacerbating the problem of modeling their
ab-initio formation. SMS models have shown that rapid collapse, with an infall
rate above a critical value, in metal-free haloes is a requirement for the
formation of a proto-stellar core which will then form an SMS. Using a
radiation hydrodynamics simulation of early galaxy formation, we show the
natural emergence of metal-free haloes both massive enough, and with
sufficiently high infall rates, to form an SMS. We find that haloes that are
exposed to both a Lyman-Werner intensity of J_LW ~ 3 J_21 and that undergo at
least one period of rapid growth early in their evolution are ideal cradles for
SMS formation. This rapid growth induces substantial dynamical heating,
amplifying the existing Lyman-Werner suppression originating from a group of
young galaxies 20 kiloparsecs away. Our results strongly indicate that
structure formation dynamics, rather than a critical Lyman-Werner (LW) flux,
may be the main driver of massive black hole formation in the early Universe.
We find that massive black hole seeds may be much more common in overdense
regions of the early Universe than previously considered with a comoving number
density up to 10^-3 Mpc^-3.
