Tidal deformability of neutron stars with realistic equations of state and their gravitational wave signatures in binary inspiral

Abstract

The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of state. The influence of a star's internal structure on the waveform is characterized by a single parameter: the tidal deformability $\ensuremath{\lambda}$, which measures the star's quadrupole deformation in response to the companion's perturbing tidal field. We calculate $\ensuremath{\lambda}$ for a wide range of equations of state and find that the value of $\ensuremath{\lambda}$ spans an order of magnitude for the range of equation of state models considered. An analysis of the feasibility of discriminating between neutron-star equations of state with gravitational wave observations of the early part of the inspiral reveals that the measurement error in $\ensuremath{\lambda}$ increases steeply with the total mass of the binary. Comparing the errors with the expected range of $\ensuremath{\lambda}$, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff equations of state, while the proposed Einstein Telescope is likely to see a clean tidal signature.