Type Ia Supernova: Burning and Detonation in the Distributed Regime

A simple, semi-analytic representation is developed for nuclear burning in Type Ia supernovae in the special case where turbulent eddies completely disrupt the flame. The speed and width of the ``distributed'' flame front are derived. For the conditions considered, the burning front can be considered as a turbulent flame brush composed of corrugated sheets of well-mixed flames. These flames are assumed to have a quasi-steady-state structure similar to the laminar flame structure, but controlled by turbulent diffusion. Detonations cannot appear in the system as long as distributed flames are still quasi-steady-state, but this condition is violated when the distributed flame width becomes comparable to the size of largest turbulent eddies. When this happens, a transition to detonation may occur. For current best estimates of the turbulent energy, the most likely density for the transition to detonation is in the range 0.5 - 1.5 x 10^7 g cm^{-3}.Comment: 12 pages, 4 figure

Cluster virial expansion for nuclear matter within a quasiparticle statistical approach

Correlations in interacting many-particle systems can lead to the formation of clusters, in particular bound states and resonances. Systematic quantum statistical approaches allow to combine the nuclear statistical equilibrium description (law of mass action) with mean-field concepts. A chemical picture, which treats the clusters as distinct entities, serves as an intuitive concept to treat the low-density limit. Within a generalized Beth-Uhlenbeck approach, the quasiparticle virial expansion is extended to include arbitrary clusters, where special attention must be paid to avoid inconsistencies such as double counting. Correlations are suppressed with increasing density due to Pauli blocking. The contribution of the continuum to the virial coefficients can be reduced by considering clusters explicitly and introducing quasiparticle energies. The cluster-virial expansion for nuclear matter joins known benchmarks at low densities with those near saturation density.Comment: 18 pages, 6 figures, 2 table

Symmetry energy of dilute warm nuclear matter

The symmetry energy of nuclear matter is a fundamental ingredient in the investigation of exotic nuclei, heavy-ion collisions and astrophysical phenomena. New data from heavy-ion collisions can be used to extract the free symmetry energy and the internal symmetry energy at subsaturation densities and temperatures below 10 MeV. Conventional theoretical calculations of the symmetry energy based on mean-field approaches fail to give the correct low-temperature, low-density limit that is governed by correlations, in particular by the appearance of bound states. A recently developed quantum statistical (QS) approach that takes the formation of clusters into account predicts symmetry energies that are in very good agreement with the experimental data. A consistent description of the symmetry energy is given that joins the correct low-density limit with quasiparticle approaches valid near the saturation density.Comment: 4 pages, 2 figures, 1 tabl

Neutron and proton drip lines using the modified Bethe-Weizsacker mass formula

Proton and neutron separation energies have been calculated using the extended Bethe-Weizsacker mass formula. This modified Bethe-Weizsacker mass formula describes minutely the positions of all the old and the new magic numbers. It accounts for the disappearance of some traditional magic numbers for neutrons and provides extra stability for some new neutron numbers. The neutron and proton drip lines have been predicted using this extended Bethe-Weizsacker mass formula. The implications of the proton drip line on the astrophysical rp-process and of the neutron drip line on the astrophysical r-process have been discussed.Comment: 5 pages, 2 figure

Constraints on the high-density nuclear equation of state from the phenomenology of compact stars and heavy-ion collisions

A new scheme for testing nuclear matter equations of state (EsoS) at high densities using constraints from neutron star phenomenology and a flow data analysis of heavy-ion collisions is suggested. An acceptable EoS shall not allow the direct Urca process to occur in neutron stars with masses below $1.5~M_{\odot}$, and also shall not contradict flow and kaon production data of heavy-ion collisions. Compact star constraints include the mass measurements of 2.1 +/- 0.2 M_sun (1 sigma level) for PSR J0751+1807, of 2.0 +/- 0.1 M_sun from the innermost stable circular orbit for 4U 1636-536, the baryon mass - gravitational mass relationships from Pulsar B in J0737-3039 and the mass-radius relationships from quasiperiodic brightness oscillations in 4U 0614+09 and from the thermal emission of RX J1856-3754. This scheme is applied to a set of relativistic EsoS constrained otherwise from nuclear matter saturation properties with the result that no EoS can satisfy all constraints simultaneously, but those with density-dependent masses and coupling constants appear most promising.Comment: 15 pages, 8 figures, 5 table

From femtonova to supernova: Heavy-ion collisions and the supernova equation of state

AB Calculations using astrophysical equations of state at low densities comparable to that of the neutrino emission surface in supernovae and accretion disks are confronted with experimental results from heavy ion collisions. An extension of previous work shows that it is important to include all of the measured experimental data to draw conclusions about the astrophysical equation of state. Armed with this information, the calculations of the astrophysical equation of state are significantly constrained. Predictions of temperatures and densities sampled in black hole accretion disks are compared to those sampled in the experimental data

Relativistic quantum kinetic equation of the Vlasov type for systems with internal degrees of freedom

We present an approach to derive a relativistic kinetic equation of the Vlasov type. Our approach is especially reliable for the description of quantum field systems with many internal degrees of freedom. The method is based on the Heisenberg picture and leads to a kinetic equation which fulfills the conservation laws. We apply the approach to the standard Walecka Lagrangian and an effective chiral Lagrangian.Comment: 11 pages, LaTeX, uses ijmpel.st

Staggering behavior of the low lying excited states of even-even nuclei in a Sp(4,R) classification scheme

We implement a high order discrete derivative analysis of the low lying collective energies of even-even nuclei with respect to the total number of valence nucleon pairs N in the framework of F- spin multiplets appearing in a symplectic sp(4,R) classification scheme. We find that for the nuclei of any given F- multiplet the respective experimental energies exhibit a Delta N=2 staggering behavior and for the nuclei of two united neighboring F- multiplets well pronounced Delta N=1 staggering patterns are observed. Those effects have been reproduced successfully through a generalized sp(4,R) model energy expression and explained in terms of the step-like changes in collective modes within the F- multiplets and the alternation of the F-spin projection in the united neighboring multiplets. On this basis we suggest that the observed Delta N=2 and Delta N=1 staggering effects carry detailed information about the respective systematic manifestation of both high order alpha - particle like quartetting of nucleons and proton (neutron) pairing interaction in nuclei.PACS number(s):21.10.Re, 21.60.FwComment: 22 pages and 6 figures changes in the figure caption

Electrical conductivity of plasmas of DB white dwarf atmospheres

The static electrical conductivity of non-ideal, dense, partially ionized helium plasma was calculated over a wide range of plasma parameters: temperatures $1\cdot 10^{4}\textrm{K} \lesssim T \lesssim 1\cdot 10^{5}\textrm{K}$ and mass density $1 \times 10^{-6} \textrm{g}/\textrm{cm}^{3} \lesssim \rho \lesssim 2 \textrm{g}/\textrm{cm}^{3}$. Calculations of electrical conductivity of plasma for the considered range of plasma parameters are of interest for DB white dwarf atmospheres with effective temperatures $1\cdot 10^{4}\textrm{K} \lesssim T_{eff} \lesssim 3\cdot 10^{4}\textrm{K}$. Electrical conductivity of plasma was calculated by using the modified random phase approximation and semiclassical method, adapted for the case of dense, partially ionized plasma. The results were compared with the unique existing experimental data, including the results related to the region of dense plasmas. In spite of low accuracy of the experimental data, the existing agreement with them indicates that results obtained in this paper are correct