NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGhent), Tea Temim (Princeton University) have captured a detailed image of supernova remnant Cassiopeia A, revealing the shell of material colliding with gas shed by the star before its explosion.
Researchers at the University of Copenhagen suggest the fate of dying massive stars, whether they become supernovae or black holes, may hinge on an often-overlooked property of neutrinos, also known as ‘ghost particles’ and their ability to change “flavor.” Their new study of 195 simulations of the collapse of stars demonstrates that neutrino flavor conversion significantly alters outcomes, particularly for stars between 16 and 30 times the mass of our sun.
“Seeing such a clear pattern across so many stars told us that neutrino flavor conversion is something we simply cannot leave out when we try to understand how massive stars end their lives,” says Mariam Gogilashvili.
Neutrino Flavor Conversion Impacts Stellar Collapse Outcomes
Researchers discovered that altering the modeling of neutrino flavor conversion, the process by which these particles change type, caused stars within this mass range to switch between exploding as supernovae and collapsing directly into black holes. This finding indicates that neutrinos can tell us something about a star’s fate and introduces a new variable in predicting a star’s ultimate fate.
Simulations of the collapse of 195 stars, each with masses ranging from 9 to 120 times that of our Sun, revealed a clear correlation between neutrino flavor conversion and the final outcome. The team systematically compared simulations with and without the inclusion of this process, varying the density at which flavor change was triggered within the star.
The resulting data demonstrated that for a significant subset of stars, the inclusion of neutrino flavor conversion flipped the predicted outcome from a supernova explosion to a direct collapse into a black hole. Mariam Gogilashvili said, “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.”
This discovery addresses what is known as the ‘supernova rate problem’, whereby researchers observe significantly fewer supernovae in the universe than theoretical models predict. Mariam Gogilashvili explained, “Normally, we detect a supernova because the explosion shines very brightly, but if a star collapses directly into a black hole without a visible explosion, or is obscured by dust, it can effectively ‘disappear’ from our counts.” Therefore, the results suggest that a mechanism could make such ‘failed supernovae’ more likely. The simulations, computationally intensive at the frontier of current capabilities, provide a potential explanation for this discrepancy, suggesting that a higher rate of direct collapse events may be occurring than previously thought.
The research highlights the importance of incorporating neutrino physics into models of stellar evolution. “We have long known that neutrinos can switch between different flavors,” said postdoctoral researcher Mariam Gogilashvili. “But we generally assumed that this had no effect on the outcome of the explosion itself.” The new research findings suggest that neutrino flavor can tell us something about the star’s fate. This could not only refine predictions about dying stars, but also improve understanding of the origins of elements in the universe, as supernova explosions are responsible for creating many of the heavier elements.
“When we study how massive stars live and die, we are also investigating the origins of many of the elements that make up the universe and ourselves,” she added. “In this way, questions about dying stars are linked to questions about our own origins.” The team’s findings, published in Physical Review D, suggest that future models of supernovae, neutron stars, and black holes must account for the complex interplay between stellar dynamics and neutrino behavior.
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.
Mariam Gogilashvili, a postdoctoral researcher at the Niels Bohr Institute and lead author of the study
Star Simulations Reveal Mass-Dependent Fate Shifts
Researchers found that the conversion of neutrinos from one “flavor” to another directly correlates with whether a dying star will explode as a supernova or collapse into a black hole, a dependency previously unacknowledged in astrophysical models. The computational demands of incorporating neutrino flavor conversion into supernova simulations previously hindered such investigations.
Irene Tamborra, professor at the Niels Bohr Institute and co-author of the study, explained that 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 because it is a problem involving a great deal of physics and it is extremely expensive computationally. To overcome this, the team developed a simplified model, comparing simulations with and without neutrino flavor conversion triggered at varying densities within the star, then measuring the resulting stellar fate.
This allowed them to isolate the impact of neutrino behavior on the final outcome. The simulations revealed a distinct pattern; stars within a specific mass range exhibited a marked shift in fate depending on whether neutrino flavor conversion was included in the model. Tamborra added, “This could therefore not only give us better tools to predict a dying star’s fate, but it may also help explain why observations do not always match theoretical predictions,” suggesting a resolution to the ‘supernova rate problem’, whereby researchers observe significantly fewer supernovae in the universe than theoretical models predict.
The team’s work indicates that neutrino flavor change isn’t merely a byproduct of stellar collapse, but an active determinant of it. The findings have implications beyond refining supernova predictions; massive stars are responsible for synthesizing heavy elements, and understanding their death throes is fundamental to tracing the origins of those elements, and ultimately, our own existence.
When we study how massive stars live and die, we are also investigating the origins of many of the elements that make up the universe and ourselves. In this way, questions about dying stars are linked to questions about our own origins.
Irene Tamborra, Professor at the Niels Bohr Institute
See today’s quantum computing news on Quantum Zeitgeist for the latest breakthroughs in qubits, hardware, algorithms, and industry deals.
