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Strange stars as persistent sources of gravitational waves

Strange stars as persistent sources of gravitational waves
Strange stars as persistent sources of gravitational waves
We investigate the relevance of the gravitational-wave driven r-mode instability for strange stars. We find that the unstable r-modes affect strange stars in a way that is quite distinct from the neutron star case. For accreting strange stars, we show that the onset of r-mode instability does not lead to the thermo-gravitational runaway that is likely to occur in neutron stars. Instead, the strange star evolves towards a quasi-equilibrium state on a time-scale of about a year. This mechanism could thus explain the clustering of spin frequencies inferred from kHz quasi-periodic oscillation data in low-mass X-ray binaries. For young strange stars, we show that the r-mode driven spin-evolution is also distinct from the neutron star case. In a young strange star, the r-mode undergoes short cycles of instability during the first few months. This is followed by a quasi-adiabatic phase where the r-mode remains at a small, roughly constant, amplitude for thousands of years. Another distinguishing feature from the neutron star case is that the r-modes in a strange star never grow to amplitudes of the order of unity. Our results suggest that the r-modes in a strange star emit a persistent gravitational-wave signal that should be detectable with large-scale interferometers given an observation time of a few months. If detected, these signals would provide unique evidence for the existence of strange stars, which would put useful constraints on the parameters of quantum chromodynamics.
1365-2966
1224-1232
Andersson, N.
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Jones, D.I.
b8f3e32c-d537-445a-a1e4-7436f472e160
Kokkotas, K.D.
7bdb71db-179a-4f68-9f5d-bd45dfea7dfc
Andersson, N.
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Jones, D.I.
b8f3e32c-d537-445a-a1e4-7436f472e160
Kokkotas, K.D.
7bdb71db-179a-4f68-9f5d-bd45dfea7dfc

Andersson, N., Jones, D.I. and Kokkotas, K.D. (2002) Strange stars as persistent sources of gravitational waves. Monthly Notices of the Royal Astronomical Society, 337 (4), 1224-1232. (doi:10.1046/j.1365-8711.2002.05837.x).

Record type: Article

Abstract

We investigate the relevance of the gravitational-wave driven r-mode instability for strange stars. We find that the unstable r-modes affect strange stars in a way that is quite distinct from the neutron star case. For accreting strange stars, we show that the onset of r-mode instability does not lead to the thermo-gravitational runaway that is likely to occur in neutron stars. Instead, the strange star evolves towards a quasi-equilibrium state on a time-scale of about a year. This mechanism could thus explain the clustering of spin frequencies inferred from kHz quasi-periodic oscillation data in low-mass X-ray binaries. For young strange stars, we show that the r-mode driven spin-evolution is also distinct from the neutron star case. In a young strange star, the r-mode undergoes short cycles of instability during the first few months. This is followed by a quasi-adiabatic phase where the r-mode remains at a small, roughly constant, amplitude for thousands of years. Another distinguishing feature from the neutron star case is that the r-modes in a strange star never grow to amplitudes of the order of unity. Our results suggest that the r-modes in a strange star emit a persistent gravitational-wave signal that should be detectable with large-scale interferometers given an observation time of a few months. If detected, these signals would provide unique evidence for the existence of strange stars, which would put useful constraints on the parameters of quantum chromodynamics.

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Published date: 2002

Identifiers

Local EPrints ID: 29446
URI: http://eprints.soton.ac.uk/id/eprint/29446
ISSN: 1365-2966
PURE UUID: a0ff2ac3-b646-4aeb-b088-5ed52eec837b
ORCID for N. Andersson: ORCID iD orcid.org/0000-0001-8550-3843
ORCID for D.I. Jones: ORCID iD orcid.org/0000-0002-0117-7567

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Date deposited: 12 May 2006
Last modified: 16 Mar 2024 03:06

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Contributors

Author: N. Andersson ORCID iD
Author: D.I. Jones ORCID iD
Author: K.D. Kokkotas

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