Joint press release Nikhef and Utrecht University
8 June 2022
New insights into neutron star matter
Combining heavy-ion experiments, astrophysical observations, and nuclear theory
An international research team has for the first time combined data from
heavy-ion experiments, gravitational wave measurements and other astronomical
observations using advanced theoretical modelling to more precisely constrain
the properties of nuclear matter as it can be found in the interior of neutron
stars. The results were published in the journal “Nature”.
Throughout the Universe, neutron stars are born in supernova explosions that
mark the end of the life of massive stars. Sometimes neutron stars are bound in
binary systems and will eventually collide with each other. These high-energy,
astrophysical phenomena feature such extreme conditions that they produce most
of the heavy elements, such as silver and gold. Consequently, neutron stars and
their collisions are unique laboratories to study the properties of matter at
densities far beyond the densities inside atomic nuclei. Heavy-ion collision
experiments conducted with particle accelerators are a complementary way to
produce and probe matter at high densities and under extreme conditions.
“Combining knowledge from nuclear theory, nuclear experiment, and astrophysical
observations is essential to shedding light on the properties of neutron-rich
matter over the entire density range probed in neutron stars,” said Sabrina
Huth from Institute of Nuclear Physics at Technical University Darmstadt, who
is one of the lead authors of the publication. Peter T. H. Pang, another lead
author from the Institute for Gravitational and Subatomic Physics (GRASP),
Utrecht University, added, “We find that constraints from collisions of gold
ions with particle accelerators show a remarkable consistency with
astrophysical observations even though they are obtained with completely
different methods.”
Recent progress in multi-messenger astronomy allowed the international research
team, involving researchers from Germany, the Netherlands, the US, and Sweden
to gain new insights to the fundamental interactions at play in nuclear matter.
In an interdisciplinary effort, the researchers included information obtained
in heavy-ion collisions into a framework combining astronomical observations of
electromagnetic signals, measurements of gravitational waves, and
high-performance astrophysics computations with theoretical nuclear physics
calculations. Their systematic study combines all these individual disciplines
for the first time, pointing to a higher pressure at intermediate densities in
neutron stars.
The authors incorporated the information from gold-ion collision experiments
performed at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt as well
as at Brookhaven National Laboratory and Lawrence Berkeley National Laboratory
in the USA in their multi-step procedure that analyzes constraints from nuclear
theory and astrophysical observations, including neutron star mass measurements
through radio observations, information from the Neutron Star Interior
Composition Explorer (NICER) mission on the International Space Station (ISS),
and multi-messenger observations of binary neutron star mergers.
Including data of heavy-ion collision in the analyses has enabled additional
constraints in the density region 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 constraints from
heavy-ion collisions can play a key role to bridge nuclear theory and
astrophysical observations by providing complementary information,” said Prof.
Dr. Chris Van Den Broeck, co-author from GRASP, Utrecht University and Nikhef.
“It is exciting to see that these studies bring together all these different
scientific communities. Further down the line, it will become possible to
understand and model not only the equation of state but also the transport
properties of matter under the most extreme conditions. In particular,
measurements from the upgraded ALICE experiment and observations with
next-generation gravitational wave detectors such as Einstein Telescope are
likely to play a significant role and contribute new insights.” said Prof. Dr.
Raimond Snellings, Scientific Director of GRASP.
More information
Nature publication:
Constraining Neutron-Star Matter with Microscopic and Macroscopic Collisions
https://www.nature.com/articles/s41586-022-04750-w ;
<https://www.nature.com/articles/s41586-022-04750-w>
Nikhef website:
https://www.nikhef.nl/news/goudbotsing-werpt-meer-licht-op-het-spul-waarvan-neutronensterren-gemaakt-zijn/
Contact
Prof. Chris Van Den Broeck, c.van.den.broeck@xxxxxxxxx
<mailto:c.van.den.broeck@xxxxxxxxx>, +31 625133968
