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Astron. Astrophys. 332, 969-983 (1998)


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Simulations of non-axisymmetric rotational core collapse

M. Rampp *, E. Müller ** and M. Ruffert ***

Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, Postfach 1523, D-85740 Garching, Germany

Received 17 November 1997 / Accepted 13 January 1998

Abstract

We report on the first three-dimensional hydrodynamic simulations of secular and dynamical non-axisymmetric instabilities in collapsing, rapidly rotating stellar cores which extend well beyond core bounce. The resulting gravitational radiation has been calculated using the quadrupole approximation.

We find that secular instabilities do not occur during the simulated time interval of several 10 ms. Models which become dynamically unstable during core collapse show a strong nonlinear growth of non-axisymmetric instabilities. Both random and coherent large scale initial perturbations eventually give rise to a dominant bar-like deformation ([FORMULA]) with [FORMULA]). In spite of the pronounced tri-axial deformation of certain parts of the core no considerable enhancement of the gravitational radiation is found. This is due to the fact that rapidly rotating cores re-expand after core bounce on a dynamical time scale before non-axisymmetric instabilities enter the nonlinear regime. Hence, when the core becomes tri-axial, it is no longer very compact.

Key words: gravitation – hydrodynamics – instabilities – stars: neutron – stars: rotation – supernovae: general – gravitational waves

* e-mail: mjr@mpa-garching.mpg.de
** e-mail: emueller@mpa-garching.mpg.de
*** e-mail: mruffert@ast.cam.ac.uk

Send offprint requests to: M. Rampp

© European Southern Observatory (ESO) 1998

Online publication: March 30, 1998
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