Inferring neutron star properties with continuous gravitational waves

TL;DR

This paper proposes a framework to infer key neutron star properties like moment of inertia and ellipticity from continuous gravitational wave detections, using Fisher analysis and simulations, without relying on electromagnetic pulsation data.

Contribution

It introduces a novel method to extract neutron star internal parameters from gravitational wave data, independent of electromagnetic observations or specific equations of state.

Findings

Errors are mainly limited by distance measurement after one year of observation.

The framework is applicable to neutron stars with known distances, including those in supernova remnants.

The methods will aid in understanding neutron star physics upon detection of continuous gravitational waves.

Abstract

Detection of continuous gravitational waves from rapidly-spinning neutron stars opens up the possibility of examining their internal physics. We develop a framework that leverages a future continuous gravitational wave detection to infer a neutron star's moment of inertia, equatorial ellipticity, and the component of the magnetic dipole moment perpendicular to its rotation axis. We assume that the neutron star loses rotational kinetic energy through both gravitational wave and electromagnetic radiation, and that the distance to the neutron star can be measured, but do not assume electromagnetic pulsations are observable or a particular neutron star equation of state. We use the Fisher information matrix and Monte Carlo simulations to estimate errors in the inferred parameters, assuming a population of gravitational-wave-emitting neutron stars consistent with the typical parameter domains of continuous gravitational wave searches. After an observation time of one year, the inferred errors for many neutron stars are limited chiefly by the error in the distance to the star. The techniques developed here will be useful if continuous gravitational waves are detected from a radio, X-ray, or gamma-ray pulsar, or else from a compact object with known distance, such as a supernova remnant.