Gravitational radiation from stellar core collapse. III - Damped ellipsoidal oscillations

Gravitational radiation from the nonspherical collapse of a rotating stellar core is calculated using homogeneous ellipsoids. The adiabatic, 'hot' equation of state for dense matter due to Lamb et al. (1978) is employed, together with a realistic hydrodynamical dissipation algorithm. It is found that the large amplitude, homologous density oscillations are effectively damped after the first few core bounces. However, small amplitude, highly eccentric oscillations about the high temperature, equilibrium density persist and can give rise to appreciable amounts of gravitational radiation. The radiation efficiency is calculated as a function of the core angular momentum. A representative gravitational waveform and its Fourier transform are presented.