Rates of observable black hole emergence in supernovae

A newly formed black hole may be directly identified if late-time accretion of material from the base of the ejected envelope generates a luminosity t hat is observable in the tail of the supernova light curve. In this work, w e estimate the rate at which events where the black hole "emerges" in the s upernova light curve can be detected with present capabilities. Our investi gation is based on an analytical model of the accretion luminosity at emerg ence as a function of progenitor mass, coupled to the inferred rate of obse rved Type II supernovae in nearby galaxies. We find through a parameter sur vey that under optimistic assumptions the potential rate of observable even ts can be as high as several per year. However, supernovae that produce bla ck holes are also likely to be low-energy explosions and therefore sublumin ous, as was the case for the best candidate to date, SN 1997D. If black hol e-forming supernovae are underdetected owing to lower luminosities, the rat e of observing black hole emergence is probably not larger than once every few years. We therefore emphasize the importance of dedicated searches for nearby supernovae as well as faint supernovae projects for improving the pr ospects of observationally certifying the supernova-black hole connection.