Low T/|W| dynamical instability in differentially rotating stars: Diagnosis with canonical angular momentum

Abstract

We study the nature of non-axisymmetric dynamical instabilities in differentially rotating stars with both linear eigenmode analysis and hydrodynamic simulations in Newtonian gravity. We especially investigate the following three types of instability; the one-armed spiral instability, the low T/|W| bar instability, and the high T/|W| bar instability, where T is the rotational kinetic energy and W is the gravitational potential energy. The nature of the dynamical instabilities is clarified by using a canonical angular momentum as a diagnostic. We find that the one-armed spiral and the low T/|W| bar instabilities occur around the corotation radius, and they grow through the inflow of canonical angular momentum around the corotation radius. The result is a clear contrast to that of a classical dynamical bar instability in high T/|W|. We also discuss the feature of gravitational waves generated from these three types of instability.

v1: 15 pages with 13 figures, mn2e.cls. Submitted to the Monthly Notices of the Royal Astronomical Society; v2: 16 pages with 17 figures, mn2e.cls. Monthly Notices of the Royal Astronomical Society (2006) in press

References in corpus (3)

• Three-dimensional simulations of stellar core collapse in full general relativity: Nonaxisymmetric dynamical instabilities
• One-armed Spiral Instability in a Low T/|W| Postbounce Supernova Core
• Dynamical bar instability in a relativistic rotational core collapse

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