N-Body Simulations of Gas-free Disc Galaxies with SMBH Seed in Binary
  Systems
  We have shown the outcome of N-body simulations of the interactions of two
disc galaxies without gas with the same mass. Both disc galaxies have halos of
dark matter, central bulges and initial supermassive black hole (SMBH) seeds at
their centers. The purpose of this work is to study the mass and dynamical
evolution of the initial SMBH seed during a Hubble cosmological time. It is a
complementation of our previous paper with different initial orbit conditions
and by introducing the SMBH seed in the initial galaxy. The disc of the
secondary galaxy has coplanar or polar orientation in relation to the disc of
the primary galaxy and their initial orbit are eccentric and prograde. The
primary and secondary galaxies have mass and size of Milky Way with an initial
SMBH seed. We have found that the merger of the primary and secondary discs can
result in a final normal disc or a final warped disc. After the fusion of
discs, the final one is thicker and larger than the initial disc. The tidal
effects are very important, modifying the evolution of the SMBH in the primary
and secondary galaxy differently. The mass of the SMBH of the primary galaxy
have increased by a factor ranging from 52 to 64 times the initial seed mass,
depending on the experiment. However, the mass of the SMBH of the secondary
galaxy have increased by a factor ranging from 6 to 33 times the initial SMBH
seed mass, depending also on the experiment. Most of the accreted particles
have come from the bulge and from the halo, depleting their particles. This
could explain why the observations show that the SMBH with masses of
approximately $10^6 M_\odot$ are found in many bulgeless galaxies. Only a small
number of the accreted particles has come from the disc. In some cases of final
merging stage of the two galaxies, the final SMBH of the secondary galaxy was
{ejected out of the galaxy}.
