Tidal deformations of neutron stars: The role of stratification and elasticity

TL;DR

This paper investigates how internal stratification and crust elasticity affect neutron star tidal deformations, finding stratification has no impact on the Love number and elasticity causes only minor corrections.

Contribution

It extends previous models by incorporating stratification and elasticity, showing stratification does not influence the Love number and elasticity effects are small.

Findings

Stratification does not affect the Love number.

Crust elasticity provides small corrections.

Results are relevant for gravitational-wave signal modeling.

Abstract

We discuss the response of neutron stars to the tidal interaction in a compact binary system, as encoded in the Love number associated with the induced deformation. This problem is of interest for gravitational-wave astronomy as there may be a detectable imprint on the signal from the late stages of binary coalescence. Previous work has focussed on simple barotropic neutron star models, providing an understanding of the role of the stellar compactness and overall density profile. We add realism to the discussion by developing the framework required to model stars with varying composition and an elastic crust. These effects are not expected to be significant for the next generation of detectors but it is nevertheless useful to be able to quantify them. Our results show that (perhaps surprisingly) internal stratification has no impact whatsoever on the Love number. We also show that crust elasticity provides a (predictably) small correction to existing models.