Gas infall into atomic cooling haloes: on the formation of protogalactic
  disks and supermassive black holes at z > 10
  We have performed cosmo-hydro simulations using the RAMSES code to study
atomic cooling (ACHs) haloes at z=10 with masses 5E7Msun<~M<~2E9Msun. We assume
primordial gas and H2-cooling and prior star-formation have been suppressed. We
analysed 19 haloes (gas and DM) at a resolution of ~10 (proper) pc, selected
from a total volume of ~2E3 (comoving) Mpc3. This is the largest statistical
hydro-sim. study of ACHs at z>10 to date. We examine the morphology, angular
momentum (AM), thermodynamic, and turbulence of these haloes, in order to
assess the prevalence of disks and supermassive black holes (SMBHs). We find no
correlation between either the magnitude or the direction of the AM of the gas
and its parent DM halo. Only 3 haloes form rotationally supported cores. Two of
the most massive haloes form massive, compact overdense blobs. These blobs have
an accretion rate ~0.5 Msun/yr (at a distance of 100 pc), and are possible
sites of SMBH formation. Our results suggest that the degree of rotational
support and the fate of the gas in a halo is determined by its large-scale
environment and merger history. In particular, the two haloes forming blobs are
located at knots of the cosmic web, cooled early on, and experienced many
mergers. The gas in these haloes is lumpy and highly turbulent, with Mach N. >~
5. In contrast, the haloes forming rotationally supported cores are relatively
more isolated, located midway along filaments, cooled more recently, and
underwent fewer mergers. Thus, the gas in these haloes is less lumpy and less
turbulent (Mach <~ 4), and could retain most of its AM. The remaining 14 haloes
have intermediate properties. If verified in a larger sample of haloes and with
additional physics, our results will have implications for observations of the
highest-redshift galaxies and quasars with JWST.
