Impact of crust-core connection procedures on the tidal deformability of neutron stars

TL;DR

This study examines how different crust-core connection methods in neutron star models influence their tidal deformability, revealing significant uncertainties especially with the direct connection approach, which impacts gravitational-wave data interpretation.

Contribution

It introduces and compares three distinct crust-core connection procedures and assesses their effects on neutron star properties, especially tidal deformability.

Findings

Mass-radius relations are largely unaffected by connection procedures.

Tidal deformability varies by over 20% depending on the connection method.

The direct connection procedure results in the largest uncertainties.

Abstract

We study the impact of crust-core connection procedures on various neutron-star properties, especially on the tidal deformability. We consider three types of connection procedures to treat the discontinuity in a nonunified equation of state around the crust-core transition: (1) the direct connection procedure, (2) the crossover connection procedure, and (3) the segmented method. Our results indicate that the mass-radius relations of neutron stars are almost unaffected by the details of the connection procedure. However, the tidal deformabilities of neutron stars are sensitive to the crust-core connection procedures. The tidal deformability is closely related to gravitational-wave measurements. For a canonical 1.4$M_\odot$ neutron star, uncertainties in the tidal deformability $\Lambda_{1.4}$ from different connection procedures can exceed 20\%. We find that the direct connection procedure yields significantly larger uncertainties in the tidal deformability, while the segmented method and crossover connection procedure provide relatively stable results.