GRAVITATIONAL-WAVES FROM THE COLLAPSE OF ROTATING STELLAR CORES

The gravitional quadrupole (and also the octupole and the hexadecapole) waves resulting from four different numerical collapse models for rotating 1.36 M.-iron cores of 20 M.-stars are calculated. The gravitional dynamics of each core collapse is treated at the Newtonian level since the highest appearing values of the central density and the velocity are 2.6 10(14) g/cm3 and 8 10(9) cm/s, respectively. Axial symmetry is assumed in all calculations. In order to determine the waveforms, we apply an analytic expression which was recently derived and which is very well adapted to numerical implementations. The four resulting waveforms, which are of high quality, show qualitatively and quantitatively different shapes, characteristic of the bounce mechanisms of the models. Inversely, the measurement of a waveform could be used to distinguish a bounce due to the incompressibility of nuclear matter from a bounce caused by centrifugal forces. The dimensionless amplitudes range up to 2 10(-23) at a distance of 10 Mpc with the maximum of the power spectrum in the frequency range 5 10(2)-10(3) Hz. The radiated energy amounts to 8 10(-8) M.c2 for the most efficient model.