Neutron stars are giant hypernuclei?

Abstract

Neutron stars are studied in the framework of Lagrangian field theory of interacting nucleons, hyperons, and mesons, which is solved in the mean field approximation. The theory is constrained to account for the four bulk properties of nuclear matter; the saturation binding and density, compressibility, and charge symmetry energy. The cores of the heavier neutron stars are found to be dominated by hyperons, and the total hyperon population for such stars is 15 percent-20 percent, depending on whether pions condense or not. The -meson, which contributes to the isospin symmetry energy, has an important influence on the baryon populations. Lepton populations are strongly suppressed and charge neutrality is achieved among the hadrons. A possible consequence for the decay time of the magnetic field of pulsars and hence for their active lifetime is mentioned.