Modelling neutron-star ocean dynamics
Modelling neutron-star ocean dynamics
We revisit the calculation of mode oscillations in the ocean of a rotating neutron star, which may be excited during thermonuclear X-ray bursts. Our present theoretical understanding of ocean modes relies heavily on the traditional approximation commonly employed in geophysics. The approximation elegantly decouples the radial and angular sectors of the perturbation problem by neglecting the vertical contribution from the Coriolis force. However, as the implicit assumptions underlying it are not as well understood as they ought to be, we examine the traditional approximation and discuss the associated mode solutions. The results demonstrate that, while the approximation may be appropriate in certain contexts, it may not be accurate for rapidly rotating neutron stars. In addition, using the shallow-water approximation, we show analytically how the solutions that resemble r-modes change their nature in neutron-star oceans to behave like gravity waves. We also outline a simple prescription for lifting Newtonian results in a shallow ocean to general relativity, making the result more realistic.
X-ray bursts, asteroseismology, neutron stars, oscillations, rotation
Gittins, Fabian
657ec875-fac3-4606-9dcd-591ef22fc9f6
Celora, Thomas
b15e9792-aae0-479a-83c5-b5c874b19fa6
Beri, Aru
69ed346a-f02a-4243-83f9-ad5ab4c4008c
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
12 May 2023
Gittins, Fabian
657ec875-fac3-4606-9dcd-591ef22fc9f6
Celora, Thomas
b15e9792-aae0-479a-83c5-b5c874b19fa6
Beri, Aru
69ed346a-f02a-4243-83f9-ad5ab4c4008c
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Gittins, Fabian, Celora, Thomas, Beri, Aru and Andersson, Nils
(2023)
Modelling neutron-star ocean dynamics.
Universe, 9 (5), [226].
(doi:10.3390/universe9050226).
Abstract
We revisit the calculation of mode oscillations in the ocean of a rotating neutron star, which may be excited during thermonuclear X-ray bursts. Our present theoretical understanding of ocean modes relies heavily on the traditional approximation commonly employed in geophysics. The approximation elegantly decouples the radial and angular sectors of the perturbation problem by neglecting the vertical contribution from the Coriolis force. However, as the implicit assumptions underlying it are not as well understood as they ought to be, we examine the traditional approximation and discuss the associated mode solutions. The results demonstrate that, while the approximation may be appropriate in certain contexts, it may not be accurate for rapidly rotating neutron stars. In addition, using the shallow-water approximation, we show analytically how the solutions that resemble r-modes change their nature in neutron-star oceans to behave like gravity waves. We also outline a simple prescription for lifting Newtonian results in a shallow ocean to general relativity, making the result more realistic.
Text
2304.05413
- Accepted Manuscript
Text
universe-09-00226-v3
- Version of Record
More information
Accepted/In Press date: 9 May 2023
Published date: 12 May 2023
Additional Information:
Funding Information:
F.G. and N.A. gratefully acknowledge support from STFC via grant number ST/V000551/1. A.B. is funded by an INSPIRE Faculty grant (DST/INSPIRE/04/2018/001265) by the Department of Science and Technology, Govt. of India. She is grateful to the Royal Society, UK and also acknowledges the financial support of ISRO under AstroSat archival Data utilization program (No. DS-2B-13013(2)/4/2019-Sec. 2).
Keywords:
X-ray bursts, asteroseismology, neutron stars, oscillations, rotation
Identifiers
Local EPrints ID: 482006
URI: http://eprints.soton.ac.uk/id/eprint/482006
ISSN: 2218-1997
PURE UUID: efdd00ac-4f0b-43b0-acef-5a55cbf86d35
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Date deposited: 15 Sep 2023 16:31
Last modified: 18 Mar 2024 04:04
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Contributors
Author:
Fabian Gittins
Author:
Thomas Celora
Author:
Aru Beri
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