Elasticity of Nuclear Pasta

The elastic properties of neutron star crusts are relevant for a variety of currently observable or near-future electromagnetic and gravitational wave phenomena. These phenomena may depend on the elastic properties of nuclear pasta found in the inner crust. We present large-scale classical molecular dynamics simulations where we deform nuclear pasta. We simulate idealized samples of nuclear pasta and describe their breaking mechanism. We also deform nuclear pasta that is arranged into many domains, similar to what is known for the ions in neutron star crusts. Our results show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of $10^{30}{\mathrm{ergs}/\mathrm{cm}}^3$ and a breaking strain greater than 0.1.

Figure 1

Simulations deforming idealized nuclear pasta. Left to right, (1) initial configuration of the pasta, (2) deformed pasta at some later time, (3) tensile stresses vs extensional strain, and (4) shear stresses vs extensional strain. Strain ${\epsilon }_r=l_r(t)-l_0$ [see Eq. (4)] is proportional to the time. Animations are available in Supplemental Material [26].

Figure 2

Multidomain simulation of strained nuclear pasta. (Top) Tensile (left) and shear stresses (right). (Bottom) Evolution of domains, identified by color, from no strain (${\epsilon }_x=0.0$) (left) to ${\epsilon }_x=0.2$ (right). Animations are in Supplemental Material [26].