Neutron stars configurations

In this contribution we reported the theoretical description of nuclear matter in the BHF approach and its various refinements, with the application to neutron star structure calculation. We pointed out the important role of TBF at high density, which is, however, strongly compensated by the inclusion of hyperons. The resulting hadronic neutron star configurations have maximum masses of only about 1.3 M , and the presence of quark matter inside the star is required in order to reach larger values. 

The results are shown in Fig. 5. We notice that the EOS calculated with the microscopic TBF produces the largest gravitational masses, with the maximum mass of the order of 2.3 M , whereas the phenomenological TBF yields a maximum mass of about 1.8 M . In the latter case, neutron stars are characterized by smaller radii and larger central densities, i.e., the Urbana TBF produce more compact stellar objects. For completeness, we also show a sequence of stellar configurations obtained using only two-body forces. In this case the maximum mass is slightly above 1.6 M , with a radius of 9 km and a central density equal to 9 times the saturation value. 

Such models were obtained and calculated for the first time in Refs. [ , ]. The appearance of the second local maximum implies the existence of a new family of stable equilibrium stellar configurations - the neutron stars with a... 

Here we will discuss two scenarios for the proto-neutron star cooling which we denote by A and B, where A stands for cooling of a star configuration with SC whereas B is a scenario without SC. The initial states for both scenarios are chosen to have the same mass Mi(A) = A(l>) for a given initial temperature of T = 60 MeV. The final states at T = 0, however, have different masses Mf(A) / Mf(B) while the total baryon number is conserved in the cooling evolution. The resulting mass differences are AM (A) = 0.06 M , A M(B) = 0.09 M and AM (A) = 0.05 Me, A M(B) = 0.07 M for the Gaussian and Lorentzian models, respectively. 

We assume that the stellar magnetic field is dipolar ( m d), and has axial symmetry everywhere. We use cylindrical coordinates (w,, z) centered on the neutron star and aligned with the stellar rotation axis. This configuration is sketched in Figure 1. We obtain the nondimensionalized equations which construct a complete set for the dynamics of reservoir ring, as following,... 

Star grew more and more dense as gravitational energy turned into a thin glow of light. The pressure inside the core increased to unbearable levels first the electrons were squeezed away from the protons, and then the protons and neutrons themselves were squeezed together into new configurations. 

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