From neutron skins and neutron matter to the neutron star crust

Abstract

We present the first Bayesian inference of neutron star crust properties to incorporate neutron skin data, including the recent PREX measurement of the neutron skin of 208Pb, combined with recent chiral effective field theory predictions of pure neutron matter with statistical errors. Using a compressible liquid drop model with an extended Skyrme energy-density functional, we obtain the most stringent constraints to date on the transition pressure Pcc=0.33−0.07+0.07 MeV fm−3 and chemical potential μcc=12.6−1.9+1,8 MeV (which control the mass, moment of inertia and thickness of a neutron star crust), the proton fractions that bracket the pasta phases yp=0.115−0.017+0.016 and ycc=0.041−0.006+0.007, as well as the relative mass and moment of inertia ΔMp/ΔMc≈ΔIp/ΔIc=0.54−0.09+0.05 and thickness ΔRp/ΔRc=0.129−0.030+0.019 of the layers of non-spherical nuclei (nuclear pasta) in the crust.

Keywords

• Neutron stars
• Nuclear matter in neutron stars
• Nucleon distribution