Elastic properties of nuclear pasta in a fully threedimensional geometry
Abstract
Realistic estimations on the elastic properties of neutron star matter are carried out with a large strain (ε ≲ 0.5) in the framework of relativisticmeanfield model with ThomasFermi approximation, where various crystalline configurations are considered in a fully threedimensional geometry with reflection symmetry. Our calculation confirms the validity of assuming Coulomb crystals for the droplet phase above neutron drip density, which nonetheless does not work at large densities since the elastic constants are found to be decreasing after reaching their peaks. Similarly, the analytic formulae derived in the incompressible liquiddrop model give excellent description for the rod phase at small densities, which overestimates the elastic constants at larger densities. For slabs, due to the negligence on the variations of their thicknesses, the analytic formulae from liquiddrop model agree qualitatively but not quantitatively with our numerical estimations. By fitting to the numerical results, these analytic formulae are improved by introducing dampening factors. The impacts of nuclear symmetry energy are examined adopting two parameter sets, corresponding to the slope of symmetry energy L = 41.34 and 89.39 MeV. Even with the uncertainties caused by the anisotropy in polycrystallines, the elastic properties of neutron star matter obtained with L = 41.34 and 89.39 MeV are distinctively different, results in detectable differences in various neutron star activities.
 Publication:

Physics Letters B
 Pub Date:
 April 2023
 DOI:
 10.1016/j.physletb.2023.137769
 arXiv:
 arXiv:2209.13310
 Bibcode:
 2023PhLB..83937769X
 Keywords:

 Elastic constant;
 Nuclear pasta;
 Neutron star;
 Symmetry energy;
 Nuclear Theory;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 doi:10.1016/j.physletb.2023.137769