Spiral arms, warping, and clumps formation in the Galactic center young
  stellar disk
  The Galactic center of the Milky-Way harbors a massive black hole (BH)
orbited by a diverse population of young and old stars. A significant fraction
of the youngest stars ($\sim4-7$ Myr) reside in a thin stellar disk with
puzzling properties; the disk appears to be warped, shows asymmetries, and
contains one or more clumpy structures (e.g. IRS 13). Models explaining the
clumping invoked the existence of an intermediate-mass BH of $10^{3}-10^{4}$
M$_{\odot}$, but no kinematic evidence for such a BH has been found. Here we
use extended $N$-body simulations and hybrid self-consistent field method
models to show that naturally formed residual temporal asphericity of the
hosting nuclear star cluster gives rise to torques on the disk, which lead to
changes in its orientation over time, and to recurrent formation and
dissolution of single spiral arm ($m=1$ modes) structures. The changing
orientation leads to a flapping-like behavior of the disk and to the formation
of a warped disk structure. The spiral arms may explain the over-densities in
the disk (clumping) and its observed asymmetry, without invoking the existence
of an intermediate-mass BH. The spiral arms are also important for the overall
disk evolution and can be used to constrain the structure and composition of
the nuclear stellar cluster.
