Matter effects on binary neutron star waveforms

TL;DR

This paper investigates how matter effects influence gravitational waveforms from binary neutron star mergers, demonstrating that waveform differences correlate with the neutron star's deformability parameter and assessing the detectability of these effects with current and future detectors.

Contribution

It introduces improved numerical waveforms using multiple equations of state and evaluates the measurability of matter effects, specifically the quadrupole deformability parameter, in gravitational-wave observations.

Findings

Waveform deviations increase monotonically with the deformability parameter mbda.

EOS with radius differences of 1.3 km are distinguishable at 100 Mpc.

EOS are distinguishable at 300 Mpc using hybrid waveforms and matched filtering.

Abstract

Using an extended set of equations of state and a multiple-group multiple-code collaborative effort to generate waveforms, we improve numerical-relativity-based data-analysis estimates of the measurability of matter effects in neutron-star binaries. We vary two parameters of a parameterized piecewise-polytropic equation of state (EOS) to analyze the measurability of EOS properties, via a parameter {\Lambda} that characterizes the quadrupole deformability of an isolated neutron star. We find that, to within the accuracy of the simulations, the departure of the waveform from point-particle (or spinless double black-hole binary) inspiral increases monotonically with {\Lambda}, and changes in the EOS that did not change {\Lambda} are not measurable. We estimate with two methods the minimal and expected measurability of {\Lambda} in second- and third- generation gravitational-wave detectors. The first estimate, using numerical waveforms alone, shows two EOS which vary in radius by 1.3km are distinguishable in mergers at 100Mpc. The second estimate relies on the construction of hybrid waveforms by matching to post-Newtonian inspiral, and estimates that the same EOS are distinguishable in mergers at 300Mpc. We calculate systematic errors arising from numerical uncertainties and hybrid construction, and we estimate the frequency at which such effects would interfere with template-based searches.