The Moment of Inertia of the Binary Pulsar J0737–3039A: Constraining the Nuclear Equation of State

We construct numerical models of the newly discovered binary pulsar J0737-3039A, both with a fully relativistic, uniformly rotating equilibrium code that handles arbitrary spins and in the relativistic slow-rotation approximation. We compare results for a representative sample of viable nuclear equations of state (EOSs) that span three qualitatively different classes of models for the description of nuclear matter. A future dynamical measurement of the neutron star's moment of inertia from pulsar timing data will impose significant constraints on the nuclear EOS. Even a moderately accurate measurement (≲ 10%) may be able to rule out some of these competing classes. Using the measured mass, spin, and moment of inertia to identify the optimal model computed from different EOSs, one can determine the pulsar's radius.