Surface r-modes and burst oscillations of neutron stars
Sep, 200320 pages
Published in:
- Astrophys.J. 600 (2004) 914-926
e-Print:
- astro-ph/0309764 [astro-ph]
DOI:
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Abstract: (arXiv)
We study the -modes propagating in steadily mass accreting, nuclear burning, and geometrically thin envelopes on the surface of rotating neutron stars. For the modal analysis, we construct the envelope models which are fully radiaitive or have a convective region. As the angular rotation frequency is increased, the oscillation frequency of the -modes in the thin envelopes deviates appreciably from the asymptotic frequency defined in the limit of , where is the frequency observed in the corotating frame of the star, and and are the indices of the spherical harmonic function representing the angular dependence of the modes. We find that the fundamental -modes in the convective models are destabilized by strong nuclear burning in the convective region. Because of excessive heating by nuclear buring, the corotating-frame oscillation frequency of the -modes in the convective models becomes larger, and hence the inertial-frame oscillation frequency becomes smaller, than those of the corresopnding -modes in the radiative models, where is negative for the -modes of positive . We find that the relative frequency change is always positive and becomes less than 0.01 for the fundamental -modes of at 300Hz for or at 600Hz for , where and denote the oscillation frequencies for the convective and the radiative envelope models, respectively.References(31)
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