Accuracy in Measuring the Neutron Star Mass in Gravitational Wave Parameter Estimates for Nonspinning Compact Binaries

Abstract

In gravitational wave (GW) data analysis, the parameter estimate is performed to find the physical parameters of GW sources. The result of the parameter estimate is given by a posterior probability density function, and the measurement errors can be computed by using the Fisher matrix method. Using this method, we investigate the accuracy in estimates of neutron star (NS) masses (MNS) for GWs emitted from merging compact binaries. As GW sources, we consider nonspinning binaries in which the primary component is assumed to be a NS and the companion is assumed to be a NS or a stellar-mass black hole (BH). Adopting GW signals with a signal-to-noise ratio of 10 for Advanced LIGO (Laser Interferometer Gravitational wave Observatory) sensitivity, we calculate measurement errors (σ) of MNS. We find that the errors strongly depend on the mass ratio of the companion mass (Mcom) to the NS mass (MNS). For NS-NS binaries, the fractional errors (σ/MNS) are larger than 10% only in the symmetric mass region. For BH-NS binaries, the fractional errors tend to decrease with increasing mass ratio (Mcom/MNS), and the measurement accuracies are better than those for NS-NS binaries. In this case, the errors are always smaller than ∼ 3%.