Equation of state in the gravitational collapse of stars

Explosive Nucleosynthesis

“…In 1974, Freedman noticed the importance of neutral currents in the physics of core collapse supernovae; as a result of the increased cross section of core material to neutrinos, these particles are trapped during the collapse. It was shown by Bethe et al in 1979 that one of the consequences of neutrino trapping is that the entropy of the core changes little during collapse (it remains low), leaving the collapse continue up to nuclear densities. Further compression is prevented by the repulsive component of the strong interaction (stiffness of nuclear matter), leading to the core bounce.…”

Relativistic mean field calculations of nuclear properties in early stages of stellar collapse

“…In the cold, incompressible liquid drop formalism, the nuclear matter energy of a single nucleus in a lattice, W N , is given by [2], [3] :…”

“…The nuclear abundances thus depend on the temperature dependant nuclear binding energies, and through the neutron and proton fractions X n and X p , on the neutron and proton chemical potentials µ n and µ p . The mass of the homologously collapsing core and the strength of the hydrodynamic shock after stellar core bounce are determined by the lepton fraction and consequently by the electron capture rates [3] . Since the e − -capture threshold too, depends on the nuclear binding energies it is neccessary to calculate the chemical potentials and binding energies accurately, as functions of core temperature and density.…”

“…Since it must also take into account the nuclear shell and pairing effects which persist upto temperatures 0.5 to 1 MeV, these quantum effects have to be calculated using microscopic mean-field Hartree Fock or RMF methods. Thus, EOS based on the classical liquid-drop models [3]− [7] , can only hold accurately beyond ρ trapping 10 12 gm/cm 3 and T 1 MeV where nuclear shell and pairing effects are washed out. For physical conditions before neutrino trapping sets in, the cold EOS should go smoothly into the high temperature macroscopic liquid drop model based EOS [7] .…”

Towards relativistic heavy ion collisions “by small steps towards the stars”

“…In the case of the nejtron stars (Baym, 1975) one is faced with the study of cold matter at super-nuclear densities, greater than 2.8 x 10^ gm/cm 3 . In such a regime the nuclear fluid is believed likely to undergo a phase tran sition to a Bose condensate of charged pions (Bethe, 1978;Toki, 1978). Heavy ion reactions could also result in nuclear shock waves producing densities far in excess of those thought necessary for the appearance of pion condensates.…”