17-21 July 2017
Santiago de Compostela, Facultade de Química
Europe/Madrid timezone

Symmetry energy and the neutron star core-crust transition with Gogny forces

17 Jul 2017, 18:10
Aula Química Física (Facultade de Química (USC))

Aula Química Física

Facultade de Química (USC)

Nuclear Physics Nuclear Physics I


Ms. Claudia Gonzalez-Boquera (Universitat de Barcelona)


An accurate determination of the core-crust transition is necessary in the modelling of neutron stars for astrophysical purposes. The properties of the transition are intimately related to the isospin dependence of the nuclear forces at low baryon densities. Finite-range Gogny nuclear interactions are widely used in nuclear structure calculations but there are fewer studies of neutron stars with these interactions. In this work, we investigate the core-crust transition in neutron stars using several Gogny forces and analyse the deduced crustal thickness and crustal moment of inertia of the star. In a first stage, we calculate the second-, fourth- and sixth-order coefficients of the Taylor expansion of the energy per particle of asymmetric nuclear matter in powers of the isospín asymmetry for Gogny forces. These coefficients provide information about the departure of the symmetry energy from the widely used parabolic law and can influence significantly the results for the location of the inner Edge of neutron star crusts. Next, we evaluate the neutron star core-crust transition density by looking at the onset of thermodynamical instability of the liquid core. The analysed Gogny forces predict the ranges 0.094 fm-3 ≤ ρt ≤ 0.118 fm-3 for the transition density and 0.339 MeV fm-3 ≤ Pt ≤ 0.665 MeV fm-3 for the transition pressure. The transition densities of the Gogny forces show an anticorrelation with the slope parameter L of the symmetry energy, whereas the transition pressures are not found to correlate with L. Finally, the fraction of the mass and moment of inertia of the neutron star that reside in the crust are evaluated using the forces that provide stable solutions of the Tolman-Oppenheimer-Volkov equations.

Primary author

Ms. Claudia Gonzalez-Boquera (Universitat de Barcelona)


Dr. Arnau Rios (University of Surrey) Dr. Mario Centelles (Universitat de Barcelona) Dr. Xavier Viñas (Universitat de Barcelona)

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