Gigantic stars conclude their lives with a dramatic explosion, known as a core-collapse supernova (CCSN), radiating intense light and leaving behind an ultra-dense neutron star. While these cosmic events are not unusual in the grand scheme of the universe, they only transpire once every century within our own Milky Way galaxy. Consequently, scientists eagerly seek to gather as much information as possible from the next occurrence. Zidu Lin from the University of Tennessee, Knoxville, and his team propose a multimessenger approach to observing CCSNe, allowing researchers to verify models of the shock phenomena taking place just before the star detonates.
As a star’s fusion fuel is depleted, it becomes incapable of withstanding its own gravitational pull, leaving mere seconds before its demise. In the rapid collapse that follows, the star’s matter reaches scorching temperatures of a billion kelvin, emitting gamma rays. These gamma rays disintegrate nuclei, resulting in protons combining with electrons to create neutrons and an outpouring of neutrinos. The compression halts when the core becomes so dense that further contraction is impossible. The core’s contraction then slows, stops, and reverses direction, giving rise to a shock wave. The absence of spherical symmetry in this process means that gravitational waves are produced, as suggested by models.
Lin and his collaborators realized that the development of the shock wave would be reflected in the gravitational-wave and neutrino signals released during the star’s final moments. They investigated whether these signals could be detected from the next CCSN in our galaxy and concluded that it is indeed possible. However, discerning between shock-wave models will require a combined analysis of data from both channels, as the conventional single-messenger approach falls short, according to Lin.