Constraints on the moment of inertia of PSR J0737-3039A from GW170817

TL;DR

This paper uses gravitational-wave data from GW170817 and universal relations among neutron star properties to estimate the moment of inertia of PSR J0737-3039A, providing a new constraint on neutron star physics.

Contribution

It translates tidal deformability bounds from GW170817 into a direct estimate of the pulsar's moment of inertia using universal relations.

Findings

Estimated moment of inertia: $1.15^{+0.38}_{-0.24} imes 10^{45}$ g cm$^2$

Provides a new astrophysical constraint on neutron star internal structure

Future measurements could test the universality of the neutron-star equation of state.

Abstract

Continued observation of PSR J0737-3039, the double pulsar, is expected to yield a precise determination of its primary component's moment of inertia in the next few years. Since the moment of inertia depends sensitively on the neutron star's internal structure, such a measurement will constrain the equation of state of ultra-dense matter, which is believed to be universal. Independent equation-of-state constraints have already been established by the gravitational-wave measurement of the neutron-star tidal deformability in GW170817. Here, using well-known universal relations among neutron star observables, we translate the reported 90%-credible bounds on tidal deformability into a direct constraint, $I_{\star} = 1.15^{+0.38}_{-0.24} \times 10^{45} \text{ g cm}^2$, on the moment of inertia of PSR J0737-3039A. Should a future astrophysical measurement of $I_{\star}$ disagree with this prediction, it could indicate a breakdown in the universality of the neutron-star equation of state.