Unstable g-modes in Proto-Neutron Stars

In this paper we study the possibility that, due to nonlinear couplings, unstable g-modes associated with convective motions excite stable oscillating g-modes. This problem is of particular interest, since the gravitational waves emitted by a newly born proto-neutron star pulsating in its stable g-modes would be in the bandwidth of VIRGO and LIGO. Our results indicate that the nonlinear saturation of unstable modes occurs at relatively low amplitudes, and therefore, even if there exists a coupling between the stable and unstable modes, it does not seem to be sufficiently effective to explain, alone, the excitation of the oscillating g-modes found in hydrodynamical simulations.