Perturbation theory for post-Newtonian neutron stars
Perturbation theory for post-Newtonian neutron stars
Neutron stars are compact, relativistic bodies that host several extremes of modern physics. An exciting development in recent years has been the opportunity to probe this exotic physics by observing compact-binary coalescences using sensitive gravitational-wave and electromagnetic instruments. To maximise the science inferred from these measurements, we require models that accurately represent the physics. In this study, we consider the post-Newtonian approximation to general relativity for the modelling of neutron-star dynamics, with a particular view to model dynamical tides at the late stages of binary inspiral. We develop the post-Newtonian perturbation equations for a non-rotating star and show that the perturbation problem is Hermitian and therefore derives from a fundamental Lagrangian. Establishing this Lagrangian system leads to a conserved symplectic product and canonical energy for the perturbations. We determine the orthogonality condition for the post-Newtonian oscillation modes, which in turn forms the foundation of a mode-sum representation often used for dynamical tides. Finally, we demonstrate that the perturbation formulation is unique.
hydrodynamics, neutron stars, oscillations, post-Newtonian theory
Gittins, Fabian
657ec875-fac3-4606-9dcd-591ef22fc9f6
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Yin, Shanshan
1a1d6d2f-3b19-4ac9-9151-e496b32be131
4 July 2025
Gittins, Fabian
657ec875-fac3-4606-9dcd-591ef22fc9f6
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Yin, Shanshan
1a1d6d2f-3b19-4ac9-9151-e496b32be131
Gittins, Fabian, Andersson, Nils and Yin, Shanshan
(2025)
Perturbation theory for post-Newtonian neutron stars.
Classical and Quantum Gravity, 42 (13), [135014].
(doi:10.1088/1361-6382/ade83f).
Abstract
Neutron stars are compact, relativistic bodies that host several extremes of modern physics. An exciting development in recent years has been the opportunity to probe this exotic physics by observing compact-binary coalescences using sensitive gravitational-wave and electromagnetic instruments. To maximise the science inferred from these measurements, we require models that accurately represent the physics. In this study, we consider the post-Newtonian approximation to general relativity for the modelling of neutron-star dynamics, with a particular view to model dynamical tides at the late stages of binary inspiral. We develop the post-Newtonian perturbation equations for a non-rotating star and show that the perturbation problem is Hermitian and therefore derives from a fundamental Lagrangian. Establishing this Lagrangian system leads to a conserved symplectic product and canonical energy for the perturbations. We determine the orthogonality condition for the post-Newtonian oscillation modes, which in turn forms the foundation of a mode-sum representation often used for dynamical tides. Finally, we demonstrate that the perturbation formulation is unique.
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Perturbation theory for post-Newtonian neutron stars
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Accepted/In Press date: 25 June 2025
Published date: 4 July 2025
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Keywords:
hydrodynamics, neutron stars, oscillations, post-Newtonian theory
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Local EPrints ID: 503949
URI: http://eprints.soton.ac.uk/id/eprint/503949
ISSN: 0264-9381
PURE UUID: 2685edb0-2535-4d23-93d3-a6b1cf8a2fdd
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Date deposited: 19 Aug 2025 16:31
Last modified: 21 Aug 2025 02:38
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Author:
Fabian Gittins
Author:
Shanshan Yin
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