Compact object formation and the supernova explosion engine

When a massive star ends its life, its core collapses, forming a neutron star or black hole and producing some of the most energetic explosions in the universe. Core-collapse supernovae and long-duration gamma-ray bursts are the violent signatures of compact remnant formation. As such, both fields are intertwined and, coupled with theory, observations of transients can help us better understand compact remnants just as neutron star and black hole observations can constrain the supernova and gamma-ray burst engine. We review these ties in this paper.