Representation of the artist showing the simulation of two merging neutron stars (left) and the emerging particle tracks that can be seen in a collision of heavy ions (right) that creates matter in conditions similar to the laboratory . Credits: Tim Dietrich, Arnaud Le Fevre, Kees Huyser, ESA / Hubble, Sloan Digital Sky Survey
An international research team has for the first time combined data from experiments with heavy ions, gravitational wave measurements and other astronomical observations using advanced theoretical modeling to more accurately restrict the properties of nuclear matter as can be found in the inside the neutron stars. The results were published in the journal Nature.
Across the universe, neutron stars are born in supernova explosions that mark the end of the life of massive stars. Sometimes neutron stars are bound together in binary systems and will eventually collide with each other. These high-energy astrophysical phenomena have such extreme conditions that they produce most heavy elements, such as silver and gold. Consequently, neutron stars and their collisions are unique laboratories for studying the properties of matter at densities well beyond the densities within atomic nuclei. Heavy ion collision experiments performed with particle accelerators are a complementary way of producing and probing matter at high densities and under extreme conditions.
New knowledge about the fundamental interactions at stake in nuclear matter
“The combination of knowledge of nuclear theory, nuclear experiment, and astrophysical observations is essential to illuminating the properties of neutron-rich matter across the density range probed by neutron stars,” said Sabrina Huth. , Institute of Nuclear Physics, Darmstadt Technical University. who is one of the main authors of the publication. Peter TH Pang, another lead author at the Institute for Gravitational and Subatomic Physics (GRASP) at Utrecht University, added: “We find that the limitations of gold ion collisions with accelerators of particles show remarkable coherence with astrophysical observations even though they are obtained by completely different methods. “
Recent advances in multi-messenger astronomy have allowed the international research team, which included researchers from Germany, the Netherlands, the United States, and Sweden, to gain new insights into the key interactions at stake in nuclear matter. In an interdisciplinary effort, the researchers included information obtained from heavy ion collisions in a framework that combines astronomical observations of electromagnetic signals, gravitational wave measurements, and high-performance astrophysical calculations with theoretical calculations of nuclear physics. His systematic study combines all these individual disciplines for the first time, pointing to a higher pressure at intermediate densities in neutron stars.
Heavy ion collision data included
The authors incorporated information from gold ion collision experiments conducted at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, as well as the Brookhaven National Laboratory and Lawrence Berkeley National Laboratory in the U.S. into their multi-step procedure that analyzes the limitations of nuclear theory and astrophysical observations. including neutron star mass measurements by radio observations, information from the Neutron Star Interior Composition Explorer (NICER) mission on the International Space Station (ISS), and observations of various binary neutron star fusion messengers .
Nuclear theorists Sabrina Huth and Achim Schwenk of Darmstadt Technical University and Ingo Tews of the Los Alamos National Laboratory were key to translating the information obtained from the collisions of heavy ions into the matter of neutron stars, which it is necessary to incorporate astrophysical limitations.
The inclusion of heavy ion collision data in the analyzes has allowed for additional limitations in the region of density where nuclear theory and astrophysical observations are less sensitive. This has helped to provide a more complete understanding of dense matter. In the future, improved limitations of heavy ion collisions may play an important role in linking nuclear theory and astrophysical observations by providing complementary information. This is especially true for experiments probing higher densities, and the reduction of experimental uncertainties has great potential to provide new limitations for the properties of neutron stars. New information on both sides can easily be included in the framework to further improve the understanding of dense matter in the coming years.
Black hole or no black hole: on the result of neutron star collisions More information: Sabrina Huth et al, Constraining neutron-star matter with microscopic and macroscopic collisions, Nature (2022). DOI: 10.1038 / s41586-022-04750-w Provided by Darmstadt Technical University
Citation: New Knowledge on the Matter of Neutron Stars (2022, June 8) Retrieved June 8, 2022 from
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