The Shear Viscosity and Thermal Conductivity of Nuclear Pasta

Abstract

We calculate the shear viscosity $η$ and thermal conductivity $κ$ of a nuclear pasta phase in neutron star crusts. This involves complex non-spherical shapes. We use semiclassical molecular dynamics simulations involving 40,000 to 100,000 nucleons. The viscosity $η$ can be simply expressed in terms of the height $Z^*$ and width $Δq$ of the peak in the static structure factor $S_p(q)$. We find that $η$ increases somewhat, compared to a lower density phase involving spherical nuclei, because $Z^*$ decreases from form factor and ion screening effects. However, we do not find a dramatic increase in $η$ from non-spherical shapes, as may occur in conventional complex fluids.