Dynamical tidal response of neutron stars as a probe of dense-matter properties

TL;DR

This paper investigates how the internal structure of neutron stars influences their dynamical tidal response, highlighting potential for gravitational-wave observations to probe dense matter properties.

Contribution

It introduces analytic models linking neutron star internal structure to tidal responses, emphasizing the role of symmetry energy coefficients in gravitational-wave signals.

Findings

Dissipative tidal effects are too small to detect with current/future observations.

Dynamical tidal response depends strongly on symmetry energy slope and higher-order coefficients.

Gravitational waves can potentially probe dense matter properties via dynamical tides.

Abstract

Dynamical tidal deformations play a crucial role in the gravitational waves emitted by binary neutron star systems during their late inspiral. In this work, we systematically explore how relativistic (dynamical and dissipative) tidal deformations depend on the internal structure of a neutron star using two analytic classes of equations of state. The first class is a nucleonic model that is parameterized by nuclear physics observables, such as the symmetry energy coefficients and saturation properties. The second class is a toy model of quark matter, the MIT bag model. To model tidal dissipation, we self-consistently include contributions from weak-interaction-driven bulk-viscous effects while considering both the nucleonic and the quark-matter equations of state. The dissipative tide is sensitive to frequency and temperature, but its magnitude, as predicted by weak-interaction-driven bulk-viscous effects, is too small (within the equation-of-state models studied here) to be detectable by current or future observations. However, we find that the (conservative) dynamical tidal response function depends strongly on the slope of the symmetry energy and on higher-order coefficients of the symmetry energy; this implies that gravitational-wave observations could be used to probe higher-order coefficients of the symmetry energy through their effect on the (conservative) dynamical tide.