The tidal response of a relativistic star

Fuente: arXiv
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Main Authors: Andersson, Nils, Counsell, Rhys, Gittins, Fabian, Ghosh, Suprovo
Format: Preprint
Published: 2025
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author Andersson, Nils
Counsell, Rhys
Gittins, Fabian
Ghosh, Suprovo
author_facet Andersson, Nils
Counsell, Rhys
Gittins, Fabian
Ghosh, Suprovo
contents We develop a fully relativistic approach for determining the response of a compact star to a time/frequency dependent (tidal) environment. The strategy involves matching the solution for the linearised fluid dynamics in the star's interior to the spacetime perturbations in the near-zone surrounding the body, along with an identification of the tidal driving and the star's response. Notably, this identification is exact in Newtonian gravity and we provide strong evidence that it remains robust also in the relativistic case. The argument does not involve a sum over the star's quasinormal modes and hence circumvents one of the obstacles that have held up the development of models for relativistic tides. Numerical results are provided, at the proof-of-principle level, for a realistic matter equation of state from the Brussels-Skyrme family, including composition stratification leading to the presence of low-frequency gravity modes. We also sketch the connection with the field-theory inspired approach to the problem, in which the tidal response is expressed in terms of asymptotic scattering amplitudes. We argue that progress in this direction is essential in order to complete the description of tides in relativistic stars.
format Preprint
id arxiv_https___arxiv_org_abs_2511_05139
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The tidal response of a relativistic star
Andersson, Nils
Counsell, Rhys
Gittins, Fabian
Ghosh, Suprovo
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
We develop a fully relativistic approach for determining the response of a compact star to a time/frequency dependent (tidal) environment. The strategy involves matching the solution for the linearised fluid dynamics in the star's interior to the spacetime perturbations in the near-zone surrounding the body, along with an identification of the tidal driving and the star's response. Notably, this identification is exact in Newtonian gravity and we provide strong evidence that it remains robust also in the relativistic case. The argument does not involve a sum over the star's quasinormal modes and hence circumvents one of the obstacles that have held up the development of models for relativistic tides. Numerical results are provided, at the proof-of-principle level, for a realistic matter equation of state from the Brussels-Skyrme family, including composition stratification leading to the presence of low-frequency gravity modes. We also sketch the connection with the field-theory inspired approach to the problem, in which the tidal response is expressed in terms of asymptotic scattering amplitudes. We argue that progress in this direction is essential in order to complete the description of tides in relativistic stars.
title The tidal response of a relativistic star
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2511.05139