Gravitational waves from newly born, hot neutron stars

We study the gravitational radiation associated with the non‐radial oscillations of newly born, hot neutron stars. The frequencies and damping times of the relevant quasi‐normal modes are computed for two different models of a proto‐neutron star, at different times of evolution, from its birth until it settles down as a cold neutron star. We find that the oscillation properties of proto‐neutron stars are remarkably different from those of their cold, old descendants, and that this affects the characteristic features of the gravitational signal emitted during the post‐collapse evolution. The consequences on the observability of these signals by resonant‐mass and interferometric detectors are analysed. We find that gravitational waves from the pulsations of a newborn proto‐neutron star in the Galaxy could be detected with a signal‐to‐noise ratio of 5 by the first‐generation interferometers, if the energy stored in the modes is greater than ∼10 −8 M ⊙ c 2 , or by a resonant antenna if it is greater than ∼10 −4 M ⊙ c 2 . In addition, since at early times the frequency of the space–time modes is much lower than that of a cold neutron star, they would also be detectable with the same signal‐to‐noise ratio if a comparable amount of energy is radiated into these modes.