Physics

Improved spin-density correlation simulations give researchers clearer insight into neutron stars

Neutrinos travel through a gas of neutrons and are sensitive to the correlation between the spin and density of the neutronic material. These correlations determine how much energy is transferred from the neutrino to the neutron. Credit: Dean Lee

When a star dies in a supernova, its remains can become a neutron star. Inside a neutron star, protons and electrons combine to form uncharged neutrons. This substance is called a neutron substance.

A team of researchers from the United States, China, Turkey, and Germany performed ab initio (i.e., based on the most fundamental principles) simulations to calculate the correlation between the spin and density of neutron matter. They used realistic nuclear interactions at higher neutron densities than previously investigated. Spin and density are the probability of finding a neutron with a particular spin direction at a particular location. These correlations determine important aspects of how neutrinos are scattered and heated in a collapsing supernova.

The study will be published in the journal Physical Review Letters.

To perform the calculations, the researchers introduced a new algorithm called the “Rank 1 Operator Method,” which significantly reduces the amount of computation required to calculate observables involving multiple particles. Rank 1 operator methods take advantage of simplifications of the complex mathematics used to calculate neutrino transport through dense nuclear matter, resulting in much more efficient calculations. Since then, rank-1 operator methods have been applied to calculations of other observables in nuclear physics and other fields.

Researchers can use the results of this new study to create realistic simulations of supernova explosions. Almost all the energy released in a nuclear collapse supernova is carried away by neutrinos. The outward flow of neutrinos energizes the neutron-rich material inside the supernova. This increases the chance of an explosion.

Further information: Yuan-Zhuo Ma et al, Structure factors of thermal neutron materials from Ab Initio Lattice Simulations using high-fidelity chiral interactions, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.232502. For arXiv: DOI: 10.48550/arxiv.2306.04500

Provided by the U.S. Department of Energy

Citation: Improved spin-density correlation simulations give researchers clearer insights into neutron stars (November 27, 2024) (https://phys.org/news/2024- Retrieved November 27, 2024 from 11-density-simulations-clearer-insights-neutron). html

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