Gravitational radiation from magnetically funnelled supernova fallback   onto a magnetar
  Protomagnetars spun up to millisecond rotation periods by supernova fallback are predicted to radiate gravitational waves via hydrodynamic instabilities for ~ 10^2 s before possibly collapsing to form a black hole. It is shown that magnetic funnelling of the accretion flow (i) creates a magnetically confined polar mountain, which boosts the gravitational wave signal, and (ii) "buries" the magnetic dipole moment, delaying the propeller phase and assisting black hole formation. 
A. Melatos, M. Priymak
astro-ph.HE