GW150914: Implications for the stochastic gravitational wave background from binary black holes

TL;DR

The paper estimates the stochastic gravitational wave background from binary black hole mergers, suggesting it could be higher than previously thought and potentially detectable by Advanced LIGO/Virgo.

Contribution

It provides the first estimate of the gravitational wave background from binary black holes based on GW150914, accounting for various formation scenarios.

Findings

Predicted energy density near 25 Hz: ~1.1 x 10^{-9} with uncertainties.

Background could be detectable by Advanced LIGO/Virgo at final sensitivity.

Results are robust across different formation models.

Abstract

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses $\gtrsim 30\, \text{M}_\odot$, suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO/Virgo band for stochastic backgrounds (near 25 Hz), we predict $\Omega_\text{GW}(f=25 Hz) = 1.1_{-0.9}^{+2.7} \times 10^{-9}$ with 90\% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO/Virgo detectors operating at their projected final sensitivity.