Detectability of Mode Resonances in Coalescing Neutron Star Binaries

TL;DR

This paper investigates the potential to detect resonant excitations of neutron star internal modes during binary inspirals through gravitational wave phase shifts, assessing detectability with Fisher-matrix analysis.

Contribution

It provides the first quantitative analysis of the gravitational wave phase shifts caused by neutron star mode resonances and their detectability with current detectors.

Findings

Resonant phase shifts of 8.1, 2.9, and 1.8 radians at 16, 32, and 64 Hz are detectable.

Mode resonances can significantly degrade the accuracy of other binary parameter measurements.

The analysis offers a method to probe neutron star internal structure via gravitational wave signals.

Abstract

Inspirals of neutron star-neutron star binaries are a promising source of gravitational waves for gravitational wave detectors like LIGO. During the inspiral, the tidal gravitational field of one of the stars can resonantly excite internal modes of the other star, resulting in a phase shift in the gravitational wave signal. We compute using a Fisher-matrix analysis how large the phase shift must be in order to be detectable. For a $1.4 M_\odot, 1.4 M_\odot$ binary the result is $\sim 8.1, 2.9$ and 1.8 radians, for resonant frequencies of $16, 32$ and 64 Hz. The measurement accuracies of the other binary parameters are degraded by inclusion of the mode resonance effect.