Measurability of the tidal deformability by gravitational waves from coalescing binary neutron stars

Combining new gravitational waveforms derived by long-term (14 to 16 orbit) numerical-relativity simulations with waveforms by an effective-one-body (EOB) formalism for coalescing binary neutron stars, we construct hybrid waveforms and estimate the measurability for the dimensionless tidal deformability of the neutron stars, Lambda by advanced gravitational-wave detectors. We focus on the equal-mass case with the total mass 2.7M(circle dot). We find that for an event at a hypothetical effective distance of D-eff = 200 Mpc, the distinguishable difference in the dimensionless tidal deformability will be approximate to 100, 400, and 800 at 1 sigma, 2 sigma, and 3 sigma levels, respectively, for Advanced LIGO. If the true equation of state is stiff and the typical neutron-star radius is R greater than or similar to 13 km, our analysis suggests that the radius will be constrained within approximate to 1 km at 2 sigma level for an event at D-eff = 200 Mpc. On the other hand, if the true equation of state is soft and the typical neutron-star radius is R less than or similar to 12 km, it will be difficult to narrow down the equation of state among many soft ones, although it is still possible to discriminate the true one from stiff equations of state with R greater than or similar to 13 km. We also find that gravitational waves from binary neutron stars will be distinguished from those from spinless binary black holes at more than 2 sigma level for an event at D-eff = 200 Mpc. The validity of the EOB formalism, Taylor-T4, and Taylor-F2 approximants as the inspiral waveform model is also examined.