GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences

Area of Science:

• Astrophysics
• Gravitational Wave Astronomy

Background:

• The LIGO Scientific and Virgo Collaborations detected GW170817, the first gravitational wave event from coalescing neutron stars.
• Distant, unresolvable binary neutron stars are now understood to contribute significantly to the astrophysical stochastic gravitational-wave background.

Purpose of the Study:

• To estimate the contribution of binary neutron stars to the astrophysical gravitational-wave background.
• To predict the total astrophysical gravitational-wave background amplitude and its potential detectability.

Main Methods:

• Utilized the merger rate of binary neutron stars estimated from GW170817.
• Calculated the combined gravitational-wave background from binary neutron stars and binary black holes.
• Predicted detectability based on Advanced LIGO and Virgo sensitivity and observation time.

Main Results:

• The total astrophysical background amplitude near 25 Hz is predicted to be Ω_GW(f=25 Hz)=1.8_{-1.3}^{+2.7}×10^{-9}.
• This is an increase compared to the background from binary black holes alone (Ω_GW(f=25 Hz)=1.1_{-0.7}^{+1.2}×10^{-9}).
• The total background may be detectable with a signal-to-noise-ratio of 3 after 40 months of observation.

Conclusions:

• Binary neutron star mergers significantly increase the expected amplitude of the astrophysical gravitational-wave background.
• The combined background has the potential to be detected by current and future gravitational wave observatories.
• This finding advances our understanding of compact binary mergers and their contribution to the cosmic gravitational wave landscape.