Ensemble inequivalence in supernova matter within a simple model

Gulminelli, F.; Raduta, Ad. R.

doi:10.1103/physrevc.85.025803

Cited by 19 publications

(29 citation statements)

References 69 publications

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“…The linear dependence obtained means that in the framework of the (N)LWM a strong attraction at low densities is always correlated to a strong repulsion at high densities. It is interesting to remark that the same is true in non-relativistic models [64][65][66][67][68]. Fig.2 shows the family of potentials constrained by Eq.…”

Section: Fig 1: (Color Online) Relations Between Parameters In Rmfmentioning

confidence: 69%

Liquid-gas phase transition in strange hadronic matter with relativistic models

2016

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International audienceBackground: The advent of new dedicated experimental programs on hyperon physics is rapidly boosting the field, and the possibility of synthetizing multiple strange hypernuclei requires the addition of the strangeness degree of freedom to the models dedicated to nuclear structure and nuclear matter studies at low energy. Purpose: We want to settle the influence of strangeness on the nuclear liquid-gas phase transition. Because of the large uncertainties concerning the hyperon sector, we do not aim at a quantitative estimation of the phase diagram but rather at a qualitative description of the phenomenology, as model independent as possible. Method: We analyze the phase diagram of low density matter composed of neutrons, protons and $\Lambda$ hyperons using a Relativistic Mean Field (RMF) model. We largely explore the parameter space to pin down generic features of the phase transition, and compare the results to ab-initio quantum Monte Carlo calculations. Results: We show that the liquid-gas phase transition is only slightly quenched by the addition of hyperons. Strangeness is seen to be an order parameter of the phase transition, meaning that dilute strange matter is expected to be unstable with respect to the formation of hyper-clusters. Conclusions: More quantitative results within the RMF model need improved functionals at low density, possibly fitted to ab-initio calculations of nuclear and $\Lambda$ matter

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Section: Fig 1: (Color Online) Relations Between Parameters In Rmfmentioning

confidence: 69%

Liquid-gas phase transition in strange hadronic matter with relativistic models

2016

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“…This contribution is a simple constant shift of each curve because of the condition ρ p = ρ el , and therefore does not change the sequence of optimal compositions as a function of the density. From a thermodynamic point of view, we can say [86] that the canonical solution is the same as without the electron contribution. However, the electron energy density is a monotonically increasing function of ρ el = ρ p , and the optimal ρ p monotonically increases with ρ B in this symmetric matter situation we are considering.…”

Section: E Phase Transitions In the Inner Crust?mentioning

confidence: 99%

“…Because of the very high electron incompressibility, the convexity observed in the baryonic part of the energy density is not present any more in the total thermodynamic potential. This is known in the literature as the quenching of the phase transition due to Coulomb frustration [84,85], and shows [86] that convexities in the (free) energy density do not necessarily correspond to instabilities in the physical system. This shows that if one wants to formulate the equilibrium problem in the grandcanonical ensemble, one has to account for the electron zero point motion.…”

Section: E Phase Transitions In the Inner Crust?mentioning

confidence: 99%

Unified treatment of subsaturation stellar matter at zero and finite temperature

2015

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33 pages, 15 figures; submitted to Phys. Rev. CInternational audienceThe standard variational derivation of stellar matter structure in the Wigner-Seitz approximation is generalized to the finite temperature situation where a wide distribution of different nuclear species can coexist in the same density and proton fraction condition, possibly out of $\beta$-equilibrium. The same theoretical formalism is shown to describe on one side the single-nucleus approximation (SNA), currently used in most core collapse supernova simulations, and on the other side the nuclear statistical equilibrium (NSE) approach, routinely employed in r- and p-process explosive nucleosynthesis problems. In particular we show that in-medium effects have to be accounted for in NSE to have a theoretical consistency between the zero and finite temperature modeling. The bulk part of these in-medium effects is analytically calculated and shown to be different from a van der Waals excluded volume term. This unified formalism allows controlling quantitatively the deviations from the SNA in the different thermodynamic conditions, as well as having a NSE model which is reliable at any arbitrarily low value of the temperature, with potential applications for neutron star cooling and accretion problems. We present different illustrative results with several mass models and effective interactions, showing the importance of accounting for the nuclear species distribution even at temperatures lower than 1 MeV

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“…A shortcoming of NSE models is the inconsistency among the energy functionals adopted for the description of unbound nucleons and nuclear species. This is the case of our previous work [26,21] where we used the selfconsistent mean-field treatment for unbound nucleons and a phenomenological liquid-drop parametrization for the cluster functional. The same is true for the work of Ref.…”

Section: Clusters In Stellar Mattermentioning

confidence: 99%

Clusterized nuclear matter in the (proto-)neutron star crust and the symmetry energy

2014

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Though generally agreed that the symmetry energy plays a dramatic role in determining the structure of neutron stars and the evolution of core-collapsing supernovae, little is known in what concerns its value away from normal nuclear matter density and, even more important, the correct definition of this quantity in the case of unhomogeneous matter. Indeed, nuclear matter traditionally addressed by meanfield models is uniform while clusters are known to exist in the dilute baryonic matter which constitutes the main component of compact objects outer shells. In the present work we investigate the meaning of symmetry energy in the case of clusterized systems and the sensitivity of the proto-neutron star composition and equation of state to the effective interaction. To this aim an improved Nuclear Statistical Equilibrium (NSE) model is developed, where the same effective interaction is consistently used to determine the clusters and unbound particles energy functionals in the self-consistent mean-field approximation. In the same framework, in-medium modifications to the cluster energies due to the presence of the nuclear gas are evaluated. We show that the excluded volume effect does not exhaust the in-medium effects and an extra isospin and density dependent energy shift has to be considered to consistently determine the composition of subsaturation stellar matter. The symmetry energy of diluted matter is seen to depend on the isovector properties of the effective interaction, but its behavior with density and its quantitative value are strongly modified by clusterization. PACS. 21.65.Mn nuclear matter equation of state -26.60.Gj Neutron star crust -21.10.Dr Binding energy nuclear

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Ensemble inequivalence in supernova matter within a simple model

Cited by 19 publications

References 69 publications

Liquid-gas phase transition in strange hadronic matter with relativistic models

Liquid-gas phase transition in strange hadronic matter with relativistic models

Unified treatment of subsaturation stellar matter at zero and finite temperature

Clusterized nuclear matter in the (proto-)neutron star crust and the symmetry energy

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