This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: As a star nears the end of its life, it faces two very different fates: It can explode as a supernova, leaving behind a neutron star, or collapse and become a black hole. What determines the outcome remains one of astrophysics' great unanswered questions.
Now, a new study from the University of Copenhagen shows that neutrinos—also known as "ghost particles"—and their ability to change "flavor" may play a far greater role in determining the fate of a dying massive star. This "flavor change"—or "neutrino flavor conversion"—means that neutrinos switch from one type to another. Their type, or flavor, affects how they interact with matter in the cores of dying stars.
"We have long known that neutrinos can switch between different flavors. But we generally assumed that this had no effect on the outcome of the explosion itself. Our new research findings suggest that this flavor can tell us something about the star's fate," says Mariam Gogilashvili, a postdoctoral researcher at the Niels Bohr Institute and lead author of the study.
Although scientists have known about neutrino flavor conversion for many years, incorporating it into supernova simulations has been too computationally demanding. "Simulating the death of a massive star is something that is pretty much at the frontier of what we can do computationally at the moment. That is because it is a problem involving a great deal of physics and it is extremely expensive computationally," says Irene Tamborra, a professor at the Niels Bohr Institute, head of the Particle Astrophysics group and the study's second author.
In their work published in the journal Physical Review D, the two astrophysicists developed a simplified model to investigate the significance of neutrino flavor changes in supernova simulations. The researchers simulated the collapse of 195 stars with masses between nine and 120 times the mass of the sun. They compared models "with" and "without" neutrino flavor conversion and investigated what happened when the process was triggered at different densities within the star.
They then assessed whether the stars exploded as supernovae or collapsed into black holes. The results showed that "the behavior of neutrinos can significantly alter the outcome," particularly for stars with masses between 16 and 30 solar masses. "It was a really exciting moment when we put all 195 simulations side by side and saw a whole range of stars flip from exploding to failing.
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