Population synthesis and parameter estimation of neutron stars with continuous gravitational waves and third-generation detectors

TL;DR

This study evaluates how third-generation gravitational wave detectors like the Einstein Telescope can improve measurement of neutron star properties through continuous gravitational wave observations, despite challenges in estimating certain parameters.

Contribution

It demonstrates the potential of advanced detectors to estimate neutron star parameters and highlights the difficulties in measuring the braking index and magnetic dipole moments.

Findings

Estimated moments of inertia with 10-100% error using Einstein Telescope.

Ellipticities can be inferred with 5-50% error.

Magnetic dipole moments are difficult to measure accurately.

Abstract

Precise measurement of stellar properties through the observation of continuous gravitational waves from spinning non-axisymmetric neutron stars can shed light onto new physics beyond terrestrial laboratories. Although hitherto undetected, prospects for detecting continuous gravitational waves improve with longer observation periods and more sensitive gravitational wave detectors. We study the capability of the Advanced Laser Interferometer Gravitational-Wave Observatory, and the Einstein Telescope to measure the physical properties of neutron stars through continuous gravitational wave observations. We simulate a population of Galactic neutron stars, assume continuous gravitational waves from the stars have been detected, and perform parameter estimation of the detected signals. Using the estimated parameters, we infer the stars' moments of inertia, ellipticities, and the components of the magnetic dipole moment perpendicular to the rotation axis. The estimation of the braking index proved challenging and is responsible for the majority of the uncertainties in the inferred parameters. Using the Einstein Telescope with an observation period of 5 yrs, point estimates using median can be made on the moments of inertia with error of ~ 10 - 100% and on the ellipticities with error of ~ 5 - 50%, subject to the inference of the braking index. The perpendicular magnetic dipole moment could not be accurately inferred for neutron stars that emit mainly gravitational waves.