Exploring universal characteristics of neutron star matter with relativistic ab initio equations of state

Starting from the relativistic realistic nucleon-nucleon (NN) interactions, the relativistic Brueckner-Hartree-Fock (RBHF) theory in the full Dirac space is employed to study neutron star properties. First, the one-to-one correspondence relation for gravitational redshift and mass is established and used to infer the masses of isolated neutron stars by combining gravitational redshift measurements. Next, the ratio of the moment of inertia I to mass times radius squared MR2 as a function of the compactness M/R is obtained, and is consistent with the universal relations in the literature. The moment of inertia for 1.338M(circle dot) pulsar PSR J0737-3039A I-1.338M circle dot is predicted to be 1.356 x 10(45), 1.381 x 10(45), and 1.407 x 10(45) g cm(2) by the RBHF theory in the full Dirac space with NN interactions Bonn A, B, and C, respectively. Finally, the quadrupole moment of neutron star is calculated under the slow-rotation and small-tidal-deformation approximation. The equations of state constructed by the RBHF theory in the full Dirac space, together with those by the projection method and momentum-independence approximation, conform to universal I-Love-Q relations as well. By combing the tidal deformability from GW170817 and the universal relations from relativistic ab initio methods, the moment of inertia of a neutron star with 1.4 solar mass is also deduced as I-1.4M circle dot = 1.22(-0.25)(+0.40) x 10(45) g cm(2).

Automated summary

This article employs the relativistic Brueckner-Hartree-Fock (RBHF) theory to study neutron star properties, providing predictions for mass, moment of inertia, and quadrupole moment using various methods.