Electromagnetic priors for black hole spindown in searches for gravitational waves from supernovae and long GRBs

Context. Some core-collapse supernovae appear to be hyper-energetic, and a subset of these are aspherical and associated with long GRBs. Aims. We use observations of electromagnetic emission from core-collapse supernovae and GRBs to impose constraints on their free energy source as a prior to searches for their gravitational wave emission. Methods. We review these events based on a finite efficiency for the conversion of spin energy to magnetic winds powering supernovae. Results. We find that some of the hyper-energetic events cannot be powered by the spindown of rapidly rotating proto-neutron stars by virtue of their limited rotational energy. They can, instead, be produced by the spindown of black holes providing a distinct prospect for gravitational-wave emission of interest to LIGO, Virgo, and the LCGT.