Coalescence Rate of Supermassive Black Hole Binaries Derived from
  Cosmological Simulations: Detection Rates for LISA and ET
  The coalescence history of massive black holes has been derived from
cosmological simulations, in which the evolution of those objects and that of
the host galaxies are followed in a consistent way. The present study indicates
that supermassive black holes having masses greater than $\sim 10^{9}
M_{\odot}$ underwent up to 500 merger events along their history. The derived
coalescence rate per comoving volume and per mass interval permitted to obtain
an estimate of the expected detection rate distribution of gravitational wave
signals ("ring-down") along frequencies accessible by the planned
interferometers either in space (LISA) or in the ground (Einstein). For LISA,
in its original configuration, a total detection rate of about $15 yr^{-1}$ is
predicted for events having a signal-to-noise ratio equal to 10, expected to
occur mainly in the frequency range $4-9 mHz$. For the Einstein gravitational
wave telescope, one event each 14 months down to one event each 4 years is
expected with a signal-to-noise ratio of 5, occurring mainly in the frequency
interval $10-20 Hz$. The detection of these gravitational signals and their
distribution in frequency would be in the future an important tool able to
discriminate among different scenarios explaining the origin of supermassive
black holes.
