Source Redshifts from GravitationalWave Observations of Binary Neutron Star Mergers
Abstract
Inspiraling compact binaries as standard sirens will become an invaluable tool for cosmology when we enter the gravitationalwave detection era. However, a degeneracy in the information carried by gravitational waves between the total restframe mass M and the redshift z of the source implies that neither can be directly extracted from the signal; only the combination M(1+z), the redshifted mass, can be directly extracted from the signal. Recent work has shown that for thirdgeneration detectors, a tidal correction to the gravitationalwave phase in the lateinspiral signal of binary neutron star systems can be used to break the massredshift degeneracy. Here, we propose to use the signature encoded in the postmerger signal allowing the accurate extraction of the intrinsic restframe mass of the source, in turn permitting the determination of source redshift and luminosity distance. The entirety of this analysis method and any subsequent cosmological inference derived from it would be obtained solely from gravitationalwave observations and, hence, would be independent of the cosmological distance ladder. Using numerical simulations of binary neutron star mergers of different mass, we model gravitationalwave signals at different redshifts and use a Bayesian parameter estimation to determine the accuracy with which the redshift and mass can be extracted. We find that for a known illustrative neutron star equation of state and using the Einstein telescope, the median of the 1σ confidence regions in redshift corresponds to ∼10%20% uncertainties at redshifts of z <0.04.
 Publication:

Physical Review X
 Pub Date:
 October 2014
 DOI:
 10.1103/PhysRevX.4.041004
 arXiv:
 arXiv:1312.1862
 Bibcode:
 2014PhRvX...4d1004M
 Keywords:

 95.85.Sz;
 04.25.D;
 98.80.k;
 Gravitational radiation magnetic fields and other observations;
 Numerical relativity;
 Cosmology;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 10 pages, 4 figures