The Birth of Binary Direct-Collapse Black Holes
  Supermassive primordial stars forming during catastrophic baryon collapse in
atomically-cooling halos at $z \sim$ 15 - 20 may be the origin of the first
quasars in the universe. However, no simulation to date has followed the
evolution of these halos at resolutions that are high enough or for times that
are long enough to determine if collapse actually produces SMSs. Here we report
new cosmological simulations of baryon collapse in atomically-cooled halos for
times that are long enough for SMSs to form and die as direct-collapse black
holes (DCBHs). We find that the high infall rates required to build up such
stars do persist until the end of their lives and could fuel the rapid growth
of their BHs thereafter. Our simulations also demonstrate that binary and even
small multiples of SMSs can form in low-spin and high-spin halos, respectively.
This discovery raises the exciting prospect of detecting gravitational waves
from DCBH mergers with LISA and tidal disruption events in the near infrared
with the {\em James Webb Space Telescope} and ground-based telescopes in the
coming decade.
