Neutron stars and nuclear repulsive forces at high densities

Abstract

An equation of state for nuclear matter at zero temperature and very high densities is proposed under the assumption of a soft repulsive core among baryons. The implications of this hypothesis on the equilibrium mass and radius of the core of a neutron star corresponding to densities larger than 1039 baryons/cm3 are examined. The results are discussed in a more general framework in which equations of state of the typeϱ=kP are taken into account. It is found that the «more rigid» equations of state (corresponding to smaller values ofk) give rise to larger equilibrium masses and radii. Moreover the soft-core equations may be represented asϱ=kP withk ranging from 1 to 2, depending on the density range. Our models lead to a maximum equilibrium mass for the star larger than 1.8 solar masses which is above Chandrasckhar’s limit. The astrophysical consequences of this result are briefly examined.