Properties of the neutron star crust: Quantifying and correlating uncertainties with improved nuclear physics

Speaker(s) Jérôme Margueron (CNRS/IN2P3, France)

Please contact or for zoom links.

The understanding of neutron star (NS) properties from fundamental nuclear physics inputs requires the precise determination of the relation between nuclear physics uncertainties and dense matter predictions. This became possible recently due to advances in theoretical efforts to predict properties of nuclei and dense nuclear matter, and advances in experimental nuclear physics that are now providing more stringent constraints. In addition, recent observations of NS radii by NICER and tidal deformabilities by the LIGO-Virgo collaboration have also reached the accuracy to better constrain the dense matter equation of state (EOS). These developments motivate the construction of models that can provide a unified description of the EOS of the crust and the core.

For this purpose we have employed the well-known compressible liquid-drop model to correlate uncertainties associated with neutron star crust properties with theoretical estimates of the uncertainties associated with the EOS of homogeneous neutron and nuclear matter. We also quantify the impact due to the finite size of nuclear clusters in the crust. We find for instance that the finite-size effects impact the crust composition, but have a negligible effect on the net isospin asymmetry in the crust, which is largely determined by the bulk properties. We also discuss the link between low density neutron matter predictions from microscopic nuclear approaches and the crust properties. Finally by adopting a unified model to describe the crust and the core of NSs and disregarding phase transition in dense matter, we tighten the correlation between their global properties such as their mass-radius relationship, moment of inertia, crust thickness, and tidal deformability with uncertainties associated with the nuclear Hamiltonians.