Stochastic Gravitational Wave Background from Coalescing Binary Black
  Holes
  We estimate the stochastic gravitational wave (GW) background signal from the
field population of coalescing binary stellar mass black holes (BHs) throughout
the Universe. This study is motivated by recent observations of BH-Wolf-Rayet
star systems and by new estimates in the metallicity abundances of star forming
galaxies that imply BH-BH systems are more common than previously assumed.
Using recent analytical results of the inspiral-merger-ringdown waveforms for
coalescing binary BH systems, we estimate the resulting stochastic GW
background signal. Assuming average quantities for the single source energy
emissions, we explore the parameter space of chirp mass and local rate density
required for detection by advanced and third generation interferometric GW
detectors. For an average chirp mass of 8.7$M_{\odot}$, we find that detection
through 3 years of cross-correlation by two advanced detectors will require a
rate density, $r_0 \geq 0.5 \rm{Mpc}^{-3} \rm{Myr}^{-1}$. Combining data from
multiple pairs of detectors can reduce this limit by up to 40%. Investigating
the full parameter space we find that detection could be achieved at rates $r_0
\sim 0.1 \rm{Mpc}^{-3} \rm{Myr}^{-1}$ for populations of coalescing binary BH
systems with average chirp masses of $\sim 15M_{\odot}$ which are predicted by
recent studies of BH-Wolf-Rayet star systems. While this scenario is at the
high end of theoretical estimates, cross-correlation of data by two Einstein
Telescopes could detect this signal under the condition $r_0 \geq 10^{-3}
\rm{Mpc}^{-3} \rm{Myr}^{-1}$. Such a signal could potentially mask a primordial
GW background signal of dimensionless energy density, $\Omega_{\rm{GW}}\sim
10^{-10}$, around the (1--500) Hz frequency range.
