The role of the boundary conditions in the Wigner-Seitz approximation applied to the neutron star inner crust

Abstract

The influence of the boundary conditions used in the Wigner-Seitz approximation applied to the neutron star inner crust is examined. The generalized energy functional method which includes neutron and proton pairing correlations is used. Predictions of two versions of the boundary conditions are compared with each other. The uncertainties in the equilibrium configuration (Z,R_c) of the crust, where Z is the proton charge and R_c the radius of the Wigner-Seitz cell, correspond to variation of Z by 2 -- 6 units and of R_c, by 1 -- 2 fm. The effect of the boundary conditions is enhanced at increasing density. These uncertainties are smaller than the variation of Z and R_c coming from the inclusion of pairing. The value of the pairing gap itself, especially at high density, can depend on the boundary condition used.