Relativistic equation of state of nuclear matter for supernova explosions and birth of neutron stars 超新星爆発及び中性子星誕生時の核物質の相対論的状態方程式の研究

博士論文

We study the equation of state of nuclear matter for supernova and neutron star using the relativistic mean field theory. The parameters in the theory are constrained by properties of finite nuclei in the wide range of the periodic table including neutron rich nuclei. We explore properties of high density nuclear matter under various environment; such as various proton mixing ratios and temperatures realized in supernova explosion and birth of neutron star. Properties of asymmetric nuclear matter with arbitrary proton fraction are obtained and compared with the parameterized equation of state which has been used in the systematic studies of supernova 　explosion. We provide a relativistic version of the table of the equation of state for studies of supernova simulation. We systematically present the physical quantities of nuclear matter at finite temperature tabulated in the table we made. We investigate the equation of state of high density matter for neutron star and supernova containing leptons under the chemical equilibrium condition. The proton fraction of neutron star matter turns out to be large because of the large symmetry energy determined by nuclear data We find that the behaviors of the neutrino fraction of supernova matter are significantly affected by the symmetry energy. In order to examine the validity of the relativistic framework and discuss the influence of the new table of the equation of state on astrophysical applications, we make comparisons of the relativistic mean field theory with the non-relativistic Hartree-Fock theory with the Skyrme interaction, which has been conventionally used for studies of nuclei and nuclear matter. We find the two frameworks provide significantly different results for the position of the drip lines and the neutron mean square radii of isotopes. We find the relativistic mean field theory describes successfully the nuclear binding energy and the nuclear charge radii simultaneously in the entire mass region and gives reasonable behaviors　for nuclear matter in the entire density regions through the comparisons with the properties obtained by the Skyrme Hartree-Fock theory. We compare properties of neutron stars and proto-neutron stars adopting the equation of state obtained by the two frameworks. The new table of the relativistic equation of state is applied to the simulation of birth of neutron stars. Effects on the cooling of proto-neutron stars and the properties of supernova neutrino are discussed by comparing with the results of simulations using the non-relativistic version of the table previously used.

東京都立大学, 1993-03-25, 博士（理学）, 甲第304号