ATOMS: ALMA Three-millimeter Observations of Massive Star-forming
  regions -- V. Hierarchical fragmentation and gas dynamics in IRDC
  G034.43+00.24
  We present new 3-mm continuum and molecular lines observations from the ATOMS
survey towards the massive protostellar clump, MM1, located in the filamentary
infrared dark cloud (IRDC), G034.43+00.24 (G34). The lines observed are the
tracers of either dense gas (e.g. HCO+/H13CO+ J = 1-0) or outflows (e.g. CS J =
2-1). The most complete picture to date of seven cores in MM1 is revealed by
dust continuum emission. These cores are found to be gravitationally bound,
with virial parameter, $\alpha_{vir}<2$. At least four outflows are identified
in MM1 with a total outflowing mass of $\sim 45 M_\odot$, and a total energy of
$\sim 1\times 10^{47}$ erg, typical of outflows from a B0-type star. Evidence
of hierarchical fragmentation, where turbulence dominates over thermal
pressure, is observed at both the cloud and the clump scales. This could be
linked to the scale-dependent, dynamical mass inflow/accretion on clump and
core scales. We therefore suggest that the G34 cloud could be undergoing a
dynamical mass inflow/accretion process linked to the multiscale fragmentation,
which leads to the sequential formation of fragments of the initial cloud,
clumps, and ultimately dense cores, the sites of star formation.
