Quantitative screening of internal anisotropic stress

Determine the quantitative extent to which a fluid envelope screens the effects of anisotropic stress, elasticity, and related internal stress distributions on neutron-star universal relations by solving the full coupled perturbation equations for specified stellar models.

Background

The paper argues that anisotropic stress confined to an interior region can affect the outer fluid solution only through matching data at the fluid–elastic interface. This suggests a screening mechanism analogous to the suppression of deep-interior equation-of-state information in the perfect-fluid problem.

Although prior calculations indicate that a fluid envelope can substantially reduce elastic corrections, the magnitude of this suppression depends on the strength, constitutive properties, and radial extent of the stressed region. A general quantitative characterization remains unresolved and requires model-specific coupled perturbation calculations.

References

Thus, the impact of anisotropic stress on the universal relations depends not only on its strength, but also on where in the star the stress is supported. The quantitative extent of such screening is model dependent and requires solving the full coupled perturbation equations, which is left for future work.

— Universal Relations for Neutron Stars from Asymptotic Analysis  (2608.19939 - Kamata et al., 20 Aug 2026) in Section 6.3.2, "Radial screening of internal stress"