State Of Hot Nuclear Matter Research Articles

Microscopic equation of state of hot nuclear matter for numerical relativity simulations

Context. A precise understanding of the equation of state (EOS) of dense and hot matter is key to modeling relativistic astrophysical environments, including core-collapse supernovae (CCSNe), protoneutron star (PNSs) evolution, and compact binary mergers. Aims. In this paper, we extend the microscopic zero-temperature BL (Bombaci and Logoteta) nuclear EOS to finite temperature and arbitrary nuclear composition. We employ this new EOS to describe hot β-stable nuclear matter and to compute various structural properties of nonrotating PNS. We also apply the EOS to perform dynamical simulations of a spherically symmetric CCSN. Methods. The EOS is derived using the finite temperature extension of the Brueckner–Bethe–Goldstone quantum many-body theory in the Brueckner–Hartree–Fock approximation. Neutron star properties are computed by solving the Tolman–Oppenheimer–Volkoff structure equations numerically. The sperically symmetric CCSN simulations are performed using the AGILE-IDSA code. Results. Our EOS models are able to reproduce typical features of both PNS and spherically symmetric CCSN simulations. In addition, our EOS model is consistent with present measured neutron star masses and particularly with the masses: M = 2.01 ± 0.04 M⊙ and M = 2.14−0.18+0.20 M⊙ of the neutron stars in PSR J0348+0432 and PSR J0740+6620 respectively. Finally, we suggest a feasible mechanism to produce low-mass black holes (M ∼ 2 M⊙) that could have far-reaching consequences for interpreting the gravitational wave event GW190814 as a BH–BH merger.

Equation of state for β-stable hot nuclear matter

We provide an equation of state for hot nuclear matter in β-equilibrium by applying a momentum-dependent effective interaction. We focus on the study of the equation of state of high-density and high-temperature nuclear matter, containing leptons (electrons and muons) under the chemical equilibrium condition in which neutrinos have left the system. Special attention is dedicated to the study of the contribution of the components of β-stable nuclear matter to the entropy per particle, a quantity of great interest for the study of structure and collapse of supernova.

Temperature dependence of the repulsive core potential in heavy-ion fusion reactions

In this work, we expand upon our previous study, the effect of hot nuclear matter on the calculation of the internuclear potential [Phys. Rev. C 84, 024612 (2011)], to the ${}^{28}\mathrm{Si}+{}^{40}\mathrm{Ca}$, ${}^{35}\mathrm{Cl}+{}^{48}\mathrm{Ti}$, and ${}^{40}\mathrm{Ar}+{}^{74}\mathrm{Ge}$ collision systems. For this purpose, we have employed the equation of state of hot nuclear matter, which is based on density-dependent Seyler-Blanchard formalism at finite temperature, to discuss the energy dependence of a repulsive core potential in the nucleon-nucleon interaction. The obtained values for strength of this potential show a linear dependence as a function of excitation energy ${E}^{*}$ (or temperature $T$) of the compound nucleus. Indeed, it is predictable that the effect of hot nuclear matter on heavy-ion reactions can be formulated by an additional energy-dependent function in the nucleon-nucleon potential.

Equation of state of hot polarized nuclear matter and heavy-ion fusion reactions

We employ the equation of state of hot polarized nuclear matter to simulate the repulsive force caused by the incompressibility effects of nuclear matter in the fusion reactions of heavy colliding ions. The results of our studies reveal that temperature effects of compound nuclei have significant importance in simulating the repulsive force on the fusion reactions for which the temperature of the compound nucleus increases up to about 2 MeV. Since the equation of state of hot nuclear matter depends upon the density and temperature of the nuclear matter, it has been suggested that, by using this equation of state, one can simulate simultaneously both the effects of the precompound nucleons' emission and the incompressibility of nuclear matter to calculate the nuclear potential in fusion reactions within a static formalism such as the double-folding (DF) model.

EQUATION OF STATE FOR DENSE SUPERNOVA MATTER

We provide an equation of state for high density supernova matter by applying a momentum-dependent effective interaction. We focus on the study of the equation of state of high density and high temperature nuclear matter containing leptons (electrons and neutrinos) under the chemical equilibrium condition. The conditions of charge neutrality and equilibrium under the β-decay process lead first to the evaluation of the lepton fractions and afterward to the evaluation of internal energy, pressure, entropy and, in total to the equation of state of hot nuclear matter for various isothermal cases. Thermal effects on the properties and equation of state of nuclear matter are evaluated and analyzed in the framework of the proposed effective interaction model. Since supernova matter is characterized by a constant entropy, we also present the thermodynamic properties for the isentropic case. Special attention is devoted to the study of the contribution of the components of β-stable nuclear matter to the entropy per particle, a quantity of great interest for the study of structure and collapse of supernovas.

Equation of state forβ-stable hot nuclear matter

We provide an equation of state for hot nuclear matter in $\ensuremath{\beta}$ equilibrium by applying a momentum-dependent effective interaction. We focus on the study of the equation of state of high-density and high-temperature nuclear matter, containing leptons (electrons and muons) under the chemical equilibrium condition in which neutrinos have left the system. The conditions of charge neutrality and equilibrium under the $\ensuremath{\beta}$-decay process lead first to the evaluation of proton and lepton fractions and then to the evaluation of internal energy, free energy, and pressure, and in total to the equation of state of hot nuclear matter. Thermal effects on the properties and equation of state of nuclear matter are assessed and analyzed in the framework of the proposed effective interaction model. Special attention is given to the study of the contribution of the components of $\ensuremath{\beta}$-stable nuclear matter to the entropy per particle, a quantity of great interest in the study of structure and collapse of supernova.

LOCV calculations of pressure in nuclear matter at finite temperature

The lowest-order constrained variational method is used to calculate the equation of state of hot nuclear matter. The calculations are performed for a wide range of densities of interest in heavy-ion collisions and astrophysics. A realistic nuclear Hamiltonian that contains N-N and N- Delta interactions and fits N-N scattering as well as nuclear matter saturation data is used. Besides spin, isospin, total angular momentum and density dependence, the correlation functions are also arranged to depend on the temperature of the system. The liquid-vapour phase equilibrium, as well as the behaviour of the effective mass in nuclear matter, is discussed.

Effects due to temperature-dependent nuclear binding energies on the equation of state for hot nuclear matter.

The influence of finite temperature nuclear effects upon the adiabatic index, for a system of nuclei, nucleons, and leptons, is discussed. It is found that the inclusion of temperature-dependent nuclear binding energies affects the behavior of the adiabats and of the adiabatic index, particularly, at low entropies.

A SIMPLE APPROACH TO STATIC PROPERTIES OF HOT NUCLEI

The energy density of nuclear system is derived based on the Skyrme forces and semi-empirical surface correption and Coulomb contribution. For the case of finite temperature, the analytical energy density, entropy density and free energy density are acquired with help of Sommerfield expansion to the Fermi-Dirac integrals. The energy, entropy, free energy per nucleon and the equation of state for hot nuclear matter and hot finite nuclei are calculated, compared and analysed. The possibility of studying dynamical evolution of hot nuclei is predicted.

Equation of state for hot nuclear matter

The authors develop an equation of state for hot nuclear matter by considering the hot nucleus as a mixture of fermions (nucleons and nuclear resonances) and bosons (pions). The several phases are treated as a relativistic quantum gas with a density-dependent internal interaction. The mixture is assumed to be in chemical equilibrium; from this assumption they derive the chemical potentials of all phases and calculate the thermodynamical functions. For the internal interaction several models are tested, some of them including a second minimum for the binding energy of nuclear matter at higher densities. It is shown that such a second minimum may lead to a phase transition, where nuclear matter changes from a mainly nucleonic state to a system consisting mostly of nucleon resonances.

Equation of state for hot nuclear matter

The equation of state and the chemical potential for nuclear matter are calculated including neutron-neutron, proton-proton and neutron-proton interactions with an arbitrary proton to neutron ratio at high temperatures and low densities.