Neutron star asteroseismology: axial crust oscillations in the Cowling approximation
Neutron star asteroseismology: axial crust oscillations in the Cowling approximation
Recent observations of quasi-periodic oscillations in the aftermath of giant flares in soft gamma-ray repeaters suggest a close coupling between the seismic motion of the crust after a major quake and the modes of oscillations in a magnetar. In this paper, we consider the purely elastic modes of oscillation in the crust of a neutron star in the relativistic Cowling approximation (disregarding any magnetic field). We determine the axial crust modes for a large set of stellar models, using a state-of-the-art crust equation of state and a wide range of core masses and radii. We also devise useful approximate formulae for the mode-frequencies. We show that the relative crust thickness is well described by a function of the compactness of the star and a parameter describing the compressibility of the crust only. Considering the observational data for SGR 1900+14 and SGR 1806?20, we demonstrate how our results can be used to constrain the mass and radius of an oscillating neutron star.
256-268
Samuelsson, Lars
ce25b720-ee5b-4b1a-af84-c38a41399a62
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
January 2007
Samuelsson, Lars
ce25b720-ee5b-4b1a-af84-c38a41399a62
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Samuelsson, Lars and Andersson, Nils
(2007)
Neutron star asteroseismology: axial crust oscillations in the Cowling approximation.
Monthly Notices of the Royal Astronomical Society, 374 (1), .
(doi:10.1111/j.1365-2966.2006.11147.x).
Abstract
Recent observations of quasi-periodic oscillations in the aftermath of giant flares in soft gamma-ray repeaters suggest a close coupling between the seismic motion of the crust after a major quake and the modes of oscillations in a magnetar. In this paper, we consider the purely elastic modes of oscillation in the crust of a neutron star in the relativistic Cowling approximation (disregarding any magnetic field). We determine the axial crust modes for a large set of stellar models, using a state-of-the-art crust equation of state and a wide range of core masses and radii. We also devise useful approximate formulae for the mode-frequencies. We show that the relative crust thickness is well described by a function of the compactness of the star and a parameter describing the compressibility of the crust only. Considering the observational data for SGR 1900+14 and SGR 1806?20, we demonstrate how our results can be used to constrain the mass and radius of an oscillating neutron star.
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Published date: January 2007
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Local EPrints ID: 48198
URI: http://eprints.soton.ac.uk/id/eprint/48198
ISSN: 1365-2966
PURE UUID: 7ba2e5f3-a142-41ec-b88c-3f7204b76ade
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Date deposited: 04 Sep 2007
Last modified: 16 Mar 2024 03:02
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Author:
Lars Samuelsson
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