Microscopic Nuclear Equation of State with Three-Body Forces and Neutron Star Structure

Abstract

We calculate static properties of non-rotating neutron stars (NS's) using a microscopic equation of state (EOS) for asymmetric nuclear matter. The EOS is computed in the framework of the Brueckner--Bethe--Goldstone many--body theory. We introduce three-body forces in order to reproduce the correct saturation point of nuclear matter. A microscopic well behaved EOS is derived. We obtain a maximum mass configuration with $M_{max}=1.8M_{\odot }$, a radius $R=9.7$ km and a central density $n_c=1.34f{m}^{-3}$. We find the proton fraction exceeds the critical value $x^{Urca}$, for the onset of direct Urca processes, at densities $n\ge 0.45f{m}^{-3}$. Therefore, in our model, NS's with masses above $M^{Urca}=0.96M_{\odot }$ can undergo very rapid cooling depending on whether or not nucleon superfluidity in the interior of the NS takes place. A comparison with other microscopic models for the EOS is done, and neutron star structure is calculated for these models too.

Comments: LaTeX, 10 pages, 4 Postscript figures included