Infalling clouds onto super-massive black hole binaries - I. Formation
  of discs, accretion and gas dynamics
  There is compelling evidence that most -if not all- galaxies harbour a
super-massive black hole (SMBH) at their nucleus, hence binaries of these
massive objects are an inevitable product of the hierarchical evolution of
structures in the universe, and represent an important but thus-far elusive
phase of galaxy evolution. Gas accretion via a circumbinary disc is thought to
be important for the dynamical evolution of SMBH binaries, as well as in
producing luminous emission that can be used to infer their properties. One
plausible source of the gaseous fuel is clumps of gas formed due to turbulence
and gravitational instabilities in the interstellar medium, that later fall
toward and interact with the binary. In this context, we model numerically the
evolution of turbulent clouds in near-radial infall onto equal-mass SMBH
binaries, using a modified version of the SPH code GADGET-3. We present a total
of 12 simulations that explore different possible pericentre distances and
relative inclinations, and show that the formation of circumbinary discs and
discs around each SMBH ('mini-discs') depend on those parameters. We also study
the dynamics of the formed discs, and the variability of the feeding rate onto
the SMBHs in the different configurations.
