Charged Ising Model of Neutron Star Matter

Abstract

Background: The inner crust of a neutron star is believed to consist of Coulomb-frustrated complex structures known as "nuclear pasta" that display interesting and unique low-energy dynamics. Purpose: To elucidate the structure and composition of the neutron-star crust as a function of temperature, density, and proton fraction. Methods: A new lattice-gas model, the "Charged-Ising Model" (CIM), is introduced to simulate the behavior of neutron-star matter. Preliminary Monte Carlo simulations on 30^3 lattices are performed for a variety of temperatures, densities, and proton fractions. Results: Results are obtained for the heat capacity, pair-correlation function, and static structure factor for a variety of conditions appropriate to the inner stellar crust. Conclusions: Although relatively simple, the CIM captures the essence of Coulomb frustration that is required to simulate the subtle dynamics of the inner stellar crust. Moreover, the computationally demanding long-range Coulomb interactions have been pre-computed at the appropriate lattice sites prior to the start of the simulation resulting in enormous computational gains. This work demonstrates the feasibility of future CIM simulations involving a large number of particles as a function of density, temperature, and proton fraction.

11 pages and 14 figures. Submitted to Phys. Rev. C

References in corpus (11)

• Color superconductivity in dense quark matter
• A highly resistive layer within the crust of X-ray pulsars limits their spin periods
• Simulation of Transitions between "Pasta" Phases in Dense Matter
• Formation of Nuclear "Pasta" in Supernovae
• The pasta phase within density dependent hadronic models
• The neutron star inner crust and symmetry energy
• Impact of nuclear "pasta" on neutrino transport in collapsing stellar cores
• Proton fraction in the inner neutron-star crust
• Ising analogue to compact-star matter
• Nearly frozen Coulomb Liquids
• Thermodynamics of compact-star matter within an ising approach

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• Complete catalog of ground-state diagrams for the general three-state lattice-gas model with nearest-neighbor interactions on a square lattice
• Multicritical Bifurcation and First-order Phase Transitions in a Three-dimensional Blume-Capel Antiferromagnet
• Characterization of the inner edge of the neutron star crust