GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

Abstract

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses ≳30M ⊙ , 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 and Advanced Virgo band for stochastic backgrounds (near 25 Hz), we predict Ω GW ðf ¼ 25 HzÞ ¼ 1.1 þ2.7 −0.9 × 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 and Advanced Virgo detectors operating at their projected final sensitivity.

Binary Black Hole Mergers in the First Advanced LIGO Observing Run

“…These predictions do not significantly change the median value of Ω GW from Ref. [190] while slightly decreasing the range; we still conclude that this background is potentially measurable by the Advanced LIGO/Virgo detectors operating at their projected design sensitivity.…”

“…VI and the corresponding combined rates in Table III, and employing the other "Fiducial" model assumptions from Ref. [190], we obtain 90% credible intervals on Ω GW . The three models agree at frequencies below 100 Hz, where Ω GW ðfÞ ∼ f 2=3 and which contain more than 99% of the signal-to-noise ratio for stochastic backgrounds, with Ω GW ðf ¼ 25 HzÞ ∼ 1.2 þ1.9 −0.9 × 10 −9 .…”

“…The full O1 merger rate can be used to update the estimate of the energy density Ω GW in the stochastic gravitationalwave background from unresolvable BBH mergers, improving on early results in Ref. [190]. Using the FIG.…”

Directional Limits on Persistent Gravitational Waves from Advanced LIGO’s First Observing Run

“…We consider three spectral indices: α = 0, corresponding to a flat energy density spectrum (expected from models of a cosmological background), α = 2/3, corresponding to the expected shape from a population of compact binary coalescences, and α = 3, corresponding to a flat strain power spectral density spectrum [17,32]. The different spectral models are summarized in Table I.…”

Measurement and subtraction of Schumann resonances at gravitational-wave interferometers

“…A SGWB from compact binary coalescences is potentially detectable by the time second-generation detectors reach design sensitivity [3]. Backgrounds from pulsars, magnetars, core-collapse supernovae, and various physical processes in the early universe are all possible as well [4][5][6], but their expected amplitudes are not as well constrained as the expected background due to compact binary coalescences. The potential for the contamination of searches for a SGWB is strong due to potential correlated environmental noise between detectors [5,[7][8][9][10][11], which would result in a systematic error in the searches.…”