Constraining neutron star tidal Love numbers with gravitational wave detectors

TL;DR

This paper demonstrates that gravitational wave detectors can constrain neutron star internal structure, specifically the tidal Love number, by analyzing low-frequency signals from neutron star mergers, providing insights into the nuclear equation of state.

Contribution

It introduces a method to constrain neutron star tidal Love numbers using low-frequency gravitational wave data, linking waveform phase shifts to internal stellar properties.

Findings

LIGO II can constrain lambda to < 2.0 x 10^{37} g cm^2 s^2 at 50 Mpc

The radius R of 1.4 solar mass neutron stars can be limited to < 13.6 km (n=0.5) or < 15.3 km (n=1.0)

Analysis of low-frequency signals (<400 Hz) reduces internal-structure correction errors

Abstract

Ground-based gravitational wave detectors may be able to constrain the nuclear equation of state using the early, low frequency portion of the signal of detected neutron star - neutron star inspirals. In this early adiabatic regime, the influence of a neutron star's internal structure on the phase of the waveform depends only on a single parameter lambda of the star related to its tidal Love number, namely the ratio of the induced quadrupole moment to the perturbing tidal gravitational field. We analyze the information obtainable from gravitational wave frequencies smaller than a cutoff frequency of 400 Hz, where corrections to the internal-structure signal are less than 10 percent. For an inspiral of two non-spinning 1.4 solar mass neutron stars at a distance of 50 Mpc, LIGO II detectors will be able to constrain lambda to lambda < 2.0 10^{37} g cm^2 s^2 with 90% confidence. Fully relativistic stellar models show that the corresponding constraint on radius R for 1.4 solar mass neutron stars would be R < 13.6 km (15.3 km) for a n=0.5 (n=1.0) polytrope.