Neutrinos Shape Universe: Ghost Particle Mystery Gets Evidence

Scientists have figured out how neutrinos shape the universe

For a long time, the influence of neutrinos on the formation of the Universe was considered a complex cosmological mystery. Now the scientists concluded that the effect of the mysterious subatomic particles can be calculated. It is being done by an international research group led by Professor Naoki Yoshida from the Institute of Physics and Mathematics of the Kavli University.

The scientists managed to create a model that accurately reflects the role of neutrinos in the evolution of the Universe. For that, a system of differential equations, known as the Vlasov-Poisson equations, was used.

With its help, explanations have been obtained of how neutrinos move in space with different values that are assigned to their mass. The velocity distribution of neutrinos gave insight into evolution over time. And then the scientists calculated how neutrinos affect the formation and evolution of individual galaxies.

The results showed that neutrinos suppress dark matter clustering. It is an indeterminate mass in the Universe and in galaxies. But neutrino-rich regions are correlated with mass accumulations of Galaxies, and the neutrino temperature changes with the neutrino mass.

Cosmological observations are considered to be the clearest experiments that estimate the neutrino mass. And you can rely on them when the simulation predictions are correct. According to lead researcher Koji Yoshikawa, the results of the study are generally consistent with theoretical predictions, as well as with the results of previous simulations.

They are important because they place limits on the unknown amount of neutrino mass. These are the lightest particles and it was possible to find out about their mass only thanks to the discovery in physics made in 2015 and awarded the Nobel Prize.

That award was received by two researchers at once for separate discoveries that are related to each other and prove that one type of neutrino is capable of transforming into another.

Reference: “Cosmological Vlasov–Poisson Simulations of Structure Formation with Relic Neutrinos: Nonlinear Clustering and the Neutrino Mass” by Kohji Yoshikawa, Satoshi Tanaka, Naoki Yoshida and Shun Saito, 30 November 2020, The Astrophysical Journal. DOI: 10.3847/1538-4357/abbd46