The Induced Surface Tension Contribution for the Equation of State of Neutron Stars

Abstract

We apply a novel equation of state (EoS) that includes the surface tension contribution induced by interparticle interaction and asymmetry between neutrons and protons, to the study of neutron star (NS) properties. This elaborated EoS is obtained from the virial expansion applied to multicomponent particle mixtures with hard core repulsion. The considered model is in full concordance with all the known properties of normal nuclear matter, provides a high-quality description of the proton flow constraints, hadron multiplicities created during the nuclear-nuclear collision experiments, and equally is consistent with astrophysical data coming from NS observations. The analysis suggests that the best model parameterization gives the incompressibility factor K 0 , symmetry energy J, and symmetry energy slope L at normal nuclear density equal to 200 MeV, 30 MeV, and 113.28 − 114.91 MeV, respectively. The mass-radius relations found for NSs computed with this EoS are consistent with astrophysical observations. Subject headings: dense matter -equation of state -stars: neutron arXiv:1805.04976v4 [astro-ph.HE]

Influence of flow constraints on the properties of the critical endpoint of symmetric nuclear matter

“…Also it is important that in a general way one can show that in contrast to other phenomenological EoS the present one obeys the Third Law of thermodynamics [16]. Furthermore, recently EoS of this type was successfully applied for modelling the neutron star interiors [27]. We consider this as another argument in favour of simple parametrization given by Eq.…”

Alternative formulation of the induced surface and curvature tensions approach

“…Comparing Eqs. (22) and 23with the ISCT EoS system (13)- (15), one can see that the expressions for system pressure are very similar. Moreover one can identify R L in Eqs.…”

“…This is highly nontrivial result, since these four parameters allow one to simultaneously reproduce the properties of normal nuclear matter (4 conditions) and the proton flow constraint (8 conditions) which in total make 12 conditions. The success of one-component IST EoS for symmetric nuclear matter [14] initiated a direction of the successful applications of such EoS to model the neutron stars properties [15,16]. Very recently the IST EoS was successfully extended to reproduce the classical second virial coefficients of light nuclei [17,18,19,20] and such an approach allowed us for the first time to simultaneously describe the hadron and light (anti-, hyper-) nuclei multiplicities measured in heavy ion collisions by the STAR BNL Collaboration at √ s N N = 200 GeV and by the ALICE CERN Collaboration at √ s N N = 2760 GeV with very high quality of data description χ 2 /dof = 1.07.…”

“…where the last result is obtained using Eqs. (14) and (15) for Σ k and K k , respectively. Note, however, that the average hard-core radius R and the average square of hard-core radius R 2 in Eq.…”

Second look to the Polyakov loop Nambu–Jona-Lasinio model at finite baryonic density

“…the APR4 EoS [54], which stands for the parameterization of the microscopic potential A18+δv+UIX, and the SLy EoS [55], are usually used as references in many nuclear and astrophysical studies. The third hadronic EoS, the IST [56] is able to fulfil many experimental and observational constraints on properties of nuclear and hadron matter. It is necessary to note that the mentioned hadronic EoSs do not include strangeness content as it only appears in quark matter due to weak processes converting d and s quarks to each other.…”