A search for young, luminous optical pulsars in extragalactic supernova remnants

A search for young optical pulsars within the remnants of four recent extragalactic supernovae and a 100 year old supernova in M31 has revealed no pulsations in the frequency range 0 to 500 Hz down to brightness limits near 100,000 solar luminosities. The data have been analyzed assuming that the spin-down of young pulsars can be approximated by a power law whose index is close to that produced by gravitational quadruple radiation, although other discrete indices were tried.