Extended equation of state for core-collapse simulations

Abstract

In stellar core-collapse events matter is heated and compressed to densities above nuclear matter saturation density. For progenitor stars with masses above roughly 25M , which eventually form black holes, the temperatures and densities reached during the collapse are so high that a traditional description in terms of electrons, nuclei, and nucleons is no longer adequate. We present here an improved equation of state containing, in addition, pions and hyperons. They become abundant in the high-temperature-and-density regime. We study the different constraints on such an equation of state, coming from both hyperonic data and observations of neutron-star properties. To test the zero-temperature versions of our new equations of state, we perform numerical simulations of the collapse of a neutron star to a black hole. We discuss the influence of the additional particles on the thermodynamic properties within the hot versions of the equation of state and we show that, in regimes relevant to core-collapse and black-hole formation, the effects of pions and hyperons on pressure, internal energy, and sound speed are not negligible.

Phase transition toward strange matter

“…[25]. In the applications shown below we will use mainly parametrization (BGI), but we have performed the calculations for the other parameter sets, too.…”

“…[10,14,17,[19][20][21][22][23][24][25]). However, if the opening of the strangeness TABLE I: Different parameter sets for the n − n, n − Λ and Λ − Λ interaction from Ref.…”

“…[39] (BGI, BGII, BGIII) and Ref. [25] degree of freedom at high baryonic density is associated with a first order phase transition, the mean field equations of state should be modified making use of the Gibbs construction [33].The possible presence of coexisting phases would in addition modify the matter composition with respect to the uncorrected mean-field predictions [34][35][36]. Both, matter composition and equation of state, are important ingredients not only in the calculations of neutrons star models, but in the hydrodynamical codes describing core collapse dynamics, too.…”

Composition of Nuclear Matter with Light Clusters and Bose–Einstein Condensation of $$\alpha $$ α Particles

“…The topics of current interest are, for example, the improvements on the supernova and warm neutron star equations of state and thermodynamics [7,8] which include the multi-cluster composition of matter [9,10,11,12,13,14,15,16,17,18,19,20,21]. Another aspect of the problem is the effects of light clusters in intermediate energy heavy ion collisions [22,23,24,25,26,27] which were extensively studied using various methods, see for example [28,29,30].…”

Equation of State of Hyperonic Nuclear Matter at Zero and Finite Temperatures with the Variational Method

“…The other type was constructed by Shen et al [8] with use of a relativistic mean field theory for uniform matter and a Thomas-Fermi approximation for non-uniform matter. Recently, new nuclear EOSs including hyperon mixing [9][10][11][12], have been developed for the numerical simulations of SNe, but the number of SN-EOSs is still limited, especially for hyperonic nuclear matter. Furthermore, even for purely nucleonic matter without hyperons, these SN-EOSs are based on phenomenological models for uniform matter.…”