On the Formation and Interaction of Multiple Supermassive Stars in
  Cosmological Flows
  Supermassive primordial stars with masses exceeding $\sim10^5\,M_{\odot}$
that form in atomically cooled halos are the leading candidates for the origin
of high-redshift quasars with $z>6$. Recent numerical simulations, however,
find that multiple accretion disks can form within a halo, each of which can
host a supermassive star. Tidal interactions between the disks can
gravitationally torque gas onto their respective stars and alter their
evolution. Later, when two satellite disks collide, the two stars can come into
close proximity. This may induce additional mass exchange between them. We
investigate the co-evolution of supermassive stars in atomically-cooled halos
driven by gravitational interactions between their disks. We find a remarkable
diversity of evolutionary outcomes. The results depend on these interactions
and how the formation and collapse times of the stars in the two disks are
correlated. They range from co-evolution as main sequence stars to main
sequence -- black hole pairs and black hole -- black hole mergers. We examine
the evolution of these secondary supermassive stars in detail and discuss the
prospects for binary interactions on much smaller scales after the disks merge
within their host halos.
