The I-Love-Q relations for superfluid neutron stars
The I-Love-Q relations for superfluid neutron stars
The I-Love-Q relations are approximate equation-of-state independent relations that connect the moment of inertia, the spin-induced quadrupole moment, and the tidal deformability of neutron stars. In this paper, we study the I-Love-Q relations for superfluid neutron stars for a general relativistic two-fluid model: one fluid being the neutron superfluid and the other a conglomerate of all charged components. We study to what extent the two-fluid dynamics might affect the robustness of the I-Love-Q relations by using a simple two-component polytropic model and a relativistic mean field model with entrainment for the equation-of-state. Our results depend crucially on the spin ratio Ωn/Ωp between the angular velocities of the neutron superfluid and the normal component. We find that the I-Love-Q relations can still be satisfied to high accuracy for superfluid neutron stars as long as the two fluids are nearly co-rotating Ωn/Ωp≈1. However, the deviations from the I-Love-Q relations increase as the spin ratio deviates from unity. In particular, the deviation of the Q-Love relation can be as large as O(10%) if Ωn/Ωp differ from unity by a few tens of percent. As Ωn/Ωp≈1 is expected for realistic neutron stars, our results suggest that the two-fluid dynamics should not affect the accuracy of any gravitational waveform models for neutron star binaries that employ the relation to connect the spin-induced quadrupole moment and the tidal deformabilit
111
Yeung, Cheung-Hei
b926c554-267a-4601-86fa-4d1cb2eb2045
Min, Lap-Ming
dfd18715-7278-4f88-b44c-bf6ec230797e
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Comer, Greg
b34e5164-7f70-4ba1-b04f-2f0ed9d19d05
20 April 2021
Yeung, Cheung-Hei
b926c554-267a-4601-86fa-4d1cb2eb2045
Min, Lap-Ming
dfd18715-7278-4f88-b44c-bf6ec230797e
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Comer, Greg
b34e5164-7f70-4ba1-b04f-2f0ed9d19d05
Yeung, Cheung-Hei, Min, Lap-Ming, Andersson, Nils and Comer, Greg
(2021)
The I-Love-Q relations for superfluid neutron stars.
Universe, 7, .
(doi:10.3390/universe7040111).
Abstract
The I-Love-Q relations are approximate equation-of-state independent relations that connect the moment of inertia, the spin-induced quadrupole moment, and the tidal deformability of neutron stars. In this paper, we study the I-Love-Q relations for superfluid neutron stars for a general relativistic two-fluid model: one fluid being the neutron superfluid and the other a conglomerate of all charged components. We study to what extent the two-fluid dynamics might affect the robustness of the I-Love-Q relations by using a simple two-component polytropic model and a relativistic mean field model with entrainment for the equation-of-state. Our results depend crucially on the spin ratio Ωn/Ωp between the angular velocities of the neutron superfluid and the normal component. We find that the I-Love-Q relations can still be satisfied to high accuracy for superfluid neutron stars as long as the two fluids are nearly co-rotating Ωn/Ωp≈1. However, the deviations from the I-Love-Q relations increase as the spin ratio deviates from unity. In particular, the deviation of the Q-Love relation can be as large as O(10%) if Ωn/Ωp differ from unity by a few tens of percent. As Ωn/Ωp≈1 is expected for realistic neutron stars, our results suggest that the two-fluid dynamics should not affect the accuracy of any gravitational waveform models for neutron star binaries that employ the relation to connect the spin-induced quadrupole moment and the tidal deformabilit
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universe-07-00111-v2
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Accepted/In Press date: 15 April 2021
Published date: 20 April 2021
Identifiers
Local EPrints ID: 456532
URI: http://eprints.soton.ac.uk/id/eprint/456532
ISSN: 2218-1997
PURE UUID: 18e172bd-74d6-4dc9-8b8e-fd6b40c8a3df
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Date deposited: 04 May 2022 17:10
Last modified: 17 Mar 2024 02:47
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Author:
Cheung-Hei Yeung
Author:
Lap-Ming Min
Author:
Greg Comer
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