What are scientists still trying to uncover about the death of massive stars and the birth of black holes or neutron stars?

Scientists are still trying to fully understand what really happens when massive stars die—why some collapse quietly into black holes, while others explode as spectacular supernovae leaving behind neutron stars. In my work, I run 3D computer simulations of these explosions and model the light they produce, the signals we can detect from Earth. This helps us uncover the mechanisms that power the blasts, the elements they create, and even how stars shed mass in the years before they die. That lost material surrounds the star and can shape how bright the explosion looks. Decoding this “post-mortem” record is key to understanding the life and evolution of massive stars.