Theory of Nuclear Matter for Neutron Stars and ... - Graduate Physics
Theory of Nuclear Matter for Neutron Stars and ... - Graduate Physics
Theory of Nuclear Matter for Neutron Stars and ... - Graduate Physics
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
2.3.5 Uni<strong>for</strong>m <strong>Matter</strong> at Zero Temperature <strong>and</strong> the SaturationConstraintsNext, we consider uni<strong>for</strong>m matter at zero temperature. Using the notation u = (ρ n +ρ p )/ρ o<strong>and</strong> x = ρ p /(ρ n +ρ p ), the bulk energy density at zero temperature is{ 3[ ])E = T o ρ o5 22/3 u 5/3 (1−x) 5/3 +x 5/3 −u(α 2 L [(1−x) 2 +x 2 ]+2α U (1−x)x+2 2/3 u 8/3 (β L′′[(1−x) 8/3 +x 8/3 ][ ]) }+β Ux(1−x)′′ (1−x) 2/3 +x 2/3 .(2.44)Figure 2.1: The energy per baryon E <strong>and</strong> pressure p <strong>for</strong> zero-temperature matter as afunction <strong>of</strong> composition Y p . The assumed saturation constraints are: ρ o = 0.16545 fm −3 ,E o = −16.533 MeV, p o = 0, S v = 31.63 MeV <strong>and</strong> S ′ v = 17.93 MeV.Fig. 2.1 shows the energy per nucleon E = E/ρ <strong>and</strong> the pressure p <strong>of</strong> uni<strong>for</strong>m matter as afunction <strong>of</strong> density <strong>and</strong> composition Y p <strong>for</strong> the case <strong>of</strong> zero-temperature matter. Obviously,there are substantial regions in which the incompressibility, (∂P/∂n) T,Yp , is negative <strong>and</strong> thematter is hydrodynamically unstable. It is straight<strong>for</strong>ward to show that the free energy canbe lowered if matter spontaneously divides into two phases <strong>of</strong> differing densities with thesame temperature. For asymmetric matter, each phase has differing compositions as well.These phases are in bulk equilibrium, which is described in the next section.16