Model-Independent Inference of Neutron Star Radii from Moment of Inertia Measurements

TL;DR

This paper introduces a new method to infer neutron star radii from moment of inertia measurements, providing bounds on the radius that depend only on physical stability and low-density equation of state assumptions.

Contribution

It develops a model-independent approach to constrain neutron star radii using moment of inertia data, relying solely on stability and low-density physics.

Findings

Moment of inertia bounds can constrain neutron star radii within ±1 km.

The method is robust under assumptions limited to densities below nuclear saturation.

Combining measurements of moment of inertia, mass, and radius enhances constraints on dense matter.

Abstract

A precise moment of inertia measurement for PSR J0737-3039A in the double pulsar system is expected within the next five years. We present here a new method of mapping the anticipated measurement of the moment of inertia directly into the neutron star structure. We determine the maximum and minimum values possible for the moment of inertia of a neutron star of a given radius based on physical stability arguments, assuming knowledge of the equation of state only at densities below the nuclear saturation density. If the equation of state is trusted up to the nuclear saturation density, we find that a measurement of the moment of inertia will place absolute bounds on the radius of PSR J0737-3039A to within $\pm$1 km. The resulting combination of moment of inertia, mass, and radius measurements for a single source will allow for new, stringent constraints on the dense-matter equation of state.