Observations of the gravitational radiation from well-localized , inspiraling compact object binaries can measure absolute source distances with high accuracy .
When coupled with an independent determination of redshift through an electromagnetic counterpart , these standard sirens can provide an excellent probe of the expansion history of the Universe and the dark energy .
Short \gamma -ray bursts , if produced by merging neutron star binaries , would be standard sirens with known redshifts detectable by ground-based GW networks such as LIGO-II , Virgo , and AIGO .
Depending upon the collimation of these GRBs , a single year of observation of their gravitational waves can measure the Hubble constant h to \sim 2 \% .
When combined with measurement of the absolute distance to the last scattering surface of the cosmic microwave background , this determines the dark energy equation of state parameter w to \sim 9 \% .
Similarly , supermassive binary black hole inspirals will be standard sirens detectable by LISA .
Depending upon the precise redshift distribution , \sim 100 sources could measure w at the \sim 4 \% level .