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| Paper: |
Oceanography of Accreting Neutron Stars: Nonradial Oscillations and Periodic X-ray Variability |
| Volume: |
135, A Half Century of Stellar Pulsation Interpretations: a Tribute to Arthur N. Cox |
| Page: |
437 |
| Authors: |
Bildsten, L.; Cumming, A.; Ushomirsky, G.; Cutler, C. |
| Abstract: |
Observations of quasi-periodic oscillations in the luminosity from many accreting neutron stars have led many to revisit a source of periodicity prevalent in many other stars: non-radial oscillations. After explaining the structure of the outer atmosphere, ocean and crust of an accreting neutron star, I will discuss the physics of the various low l surface waves and g-modes. The frequencies of the low l g-mode oscillations are in the range of 1- 20 Hz, coincident with many observations of periodic phenomena from the brightest accreting neutron stars. In addition, the thermal g-modes cannot radically change their frequency on a timescale much shorter than the thermal time at the depth where the energy resides, which is hours to days. Successful identification of a few non-radial modes with their observed frequencies would yield new information about the thermal and compositional makeup of the neutron star at densities in excess of 109 gr cm-3. I will also discuss the higher frequency surface waves and compare them to recent observational results from the Rossi X-Ray Timing Explorer. I close with a brief discussion of how rapid rotation (relative to the mode frequency) changes the mode structure and frequency of both the surface and internal gravity waves. |
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