Detectability of Gravitational Radiation from Prompt and Delayed Star Collapse to a Black Hole

We consider the emission of gravitational waves in the two proposed models for the collapse of a massive star to a black hole: the prompt collapse, in which nearly all the star collapses to a black hole in a dynamical time scale, and the delayed collapse, in which a light black hole, or a neutron star, which subsequently accretes matter, forms due to the fall-back achieving, in the neutron star case, the critical mass for black hole formation. Recent simulations strongly support this last scenario. We show that, due to the slowness of fall-back, in the delayed collapse the main burst of gravitational radiation is emitted depending on the parameters, mass and angular momentum, of the initial, light, black hole. We estimate, under different assumptions, the detectability of the emitted gravitational waves showing that such kind of collapse is not particularly suited for detection by forthcoming interferometric detectors. Detectors with high sensitivity at frequencies greater than ∼ 4÷ 5 kHz would be better suited for this kind of sources. We calculate also the final mass distribution function of single black holes.