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The w-mode instability of ultracompact relativistic stars

K. D. Kokkotas·J. Ruoff·N. Andersson
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Abstract

In this article we show that the, mainly spacetime, w-modes may become unstable in a rotating ultracompact ($R<3M$) relativistic star. We provide results for the axial modes of a rotating star in the slow rotation approximation, and demonstrate that an instability may become active in stars with an ergosphere. These results suggest that the so-called ``ergoregion instability'' discussed by other authors is, in fact, associated with the w-modes of the star. The unstable modes are found to grow on a timescale of seconds to minutes. We discuss briefly whether the instability is likely to have any astrophysical relevance.

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K. D. Kokkotas, J. Ruoff, N. Andersson. 2002-12-26. The w-mode instability of ultracompact relativistic stars. https://doi.org/10.1103/physrevd.70.043003

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