The supernova explosion consists in:
a) converting the whole core mass into energy and blowing it out into space
b) ripping the star apart, preceded by falling onto the core its outer layers
c) capturing of the outer layers of the star by the core

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks