Universal relations to measure neutron star properties from targeted r-mode searches

TL;DR

This paper explores how universal relations involving neutron star parameters can be used with r-mode gravitational wave searches to estimate neutron star properties, including moment of inertia, distance, and constraining the dense matter equation of state.

Contribution

It demonstrates the application of universal relations and the I-Love-Q relation to infer neutron star parameters from gravitational wave data, improving measurement accuracy.

Findings

Universal relations enable estimation of neutron star properties from GW data.

The method can break degeneracies in distance measurement for continuous GWs.

Measurements can constrain the dense matter equation of state.

Abstract

R-mode oscillations of rotating neutron stars(NS) are promising candidates for continuous gravitational wave (GW) observations. In our recent work, we derived universal relations of the NS parameters, compactness and dimensionless tidal deformability with the r-mode frequency. In this work, we investigate how these universal relations can be used to infer various NS intrinsic parameters following a successful detection of the r-modes. In particular, we show that for targeted r-mode searches, these universal relations along with the "I-Love-Q" relation can be used to estimate both the moment of inertia and the distance of the NS thus breaking the degeneracy of distance measurement for continuous gravitational wave(CGW) observations. We also discuss that with a prior knowledge of the distance of the NS from electromagnetic observations, these universal relations can also be used to constrain the dense matter equation of state (EOS) inside NS. We quantify the accuracy to which such measurements can be done using the Fisher information matrix for a broad range of possible, unknown parameters, for both the a-LIGO and Einstein Telescope (ET) sensitivities.