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Nonlinear r-Modes in Neutron Stars: Instability of an unstable mode

Philip Gressman·Lap-Ming Lin·Wai-Mo Suen·N. Stergioulas·John L. Friedman
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Abstract

We study the dynamical evolution of a large amplitude r-mode by numerical simulations. R-modes in neutron stars are unstable growing modes, driven by gravitational radiation reaction. In these simulations, r-modes of amplitude unity or above are destroyed by a catastrophic decay: A large amplitude r-mode gradually leaks energy into other fluid modes, which in turn act nonlinearly with the r-mode, leading to the onset of the rapid decay. As a result the r-mode suddenly breaks down into a differentially rotating configuration. The catastrophic decay does not appear to be related to shock waves at the star's surface. The limit it imposes on the r-mode amplitude is significantly smaller than that suggested by previous fully nonlinear numerical simulations.

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Philip Gressman, Lap-Ming Lin, Wai-Mo Suen, N. Stergioulas, John L. Friedman. 2003-01-06. Nonlinear r-Modes in Neutron Stars: Instability of an unstable mode. https://doi.org/10.1103/physrevd.66.041303

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