NEUTRON-STAR PROFILES IN THE RELATIVISTIC BRUECKNER-HARTREE-FOCK THEORY

We study the properties of neutron star matter and neutron stars in th e relativistic Brueckner-Hartree-Fock (RBHF) theory. Adopting the equa tion of state (EOS) in the RBHF theory, we calculate the properties of neutron star matter under the beta equilibrium condition in a wide ra nge of density. We perform the Thomas-Fermi calculation of neutron sta r matter in the crust region taking into account the change of nuclear shapes around the density, rho similar to 10(14) g/cm(3). We compare the results with the properties of dense matter in the non-relativisti c many body theory. The qualitative feature of neutron star matter in the crust is consistent with previous works. The relativistic EOS of n eutron star matter is found to be stiffer than the non-relativistic EO Ss characteristically. We found that the proton fraction of neutron st ar matter in the high density region in the RBHF theory is quite large as compared with those found in the non-relativistic calculations and allow the direct Urea process, which is crucial for the rapid cooling of neutron stars, for relatively massive neutron stars.