2023-12-28 12:16:18
MADRID, 28 Dic. (EUROPA PRESS) –
Astrophysicists led by the University of Helsinki provide the first quantitative estimate of the probability that there is Nuclei of quark matter in massive neutron stars.
They showed that, based on current astrophysical observations, the matter of this kind of elementary subatomic particle is almost inevitable in the most massive neutron stars: a quantitative estimate that the team extracted places the probability in the range of 80-90%.
The cores of neutron stars contain matter at the highest densities achieved in our current universe, with up to two solar masses of matter compressed within a 25 km sphere. diameter. In fact, these astrophysical objects can be thought of as giant atomic nuclei, whose gravity compresses their nuclei to densities that many times exceed those of individual protons and neutrons.
These densities make neutron stars interesting astrophysical objects from the point of view of nuclear and particle physics. A long-standing problem is Whether the immense central pressure of neutron stars can compress protons and neutrons into a new phase of matter, known as cold quark matter. In this exotic state of matter, individual protons and neutrons no longer exist.
“The quarks and gluons that constitute them are freed from their typical color confinement and allowed to move almost freely,” he explains. it’s a statement Aleksi Vuorinen, professor of theoretical particle physics at the University of Helsinki and author of the new research, published in Nature Communications.
The small remaining probability that all neutron stars are composed solely of nuclear matter requires that the change from nuclear matter to quark matter be a strong first-order phase transition, somewhat like that of liquid water turning into ice. . This type of rapid change in the properties of a neutron star’s matter has the potential to destabilize the star in such a way that the formation of even a tiny core of quark matter would cause the star to collapse into a black hole.
International collaboration between scientists from Finland, Norway, Germany and the United States was able to further demonstrate how the existence of quark matter nuclei could one day be confirmed or completely ruled out. The key is to be able to limit the strength of the phase transition between nuclear matter and quark matter, which is expected to be possible once a gravitational wave signal is one day recorded from the last part of a binary star merger. neutrons.
A key ingredient in obtaining the new results was a set of massive supercomputer calculations using Bayesian inference, a branch of statistical deduction in which the probabilities of different model parameters are inferred. by direct comparison with observation data.
The Bayesian component of the study allowed the researchers to derive new limits for the matter properties of neutron stars, showing that they approach so-called conformal behavior near the cores of the most massive stable neutron stars.
#evidence #exotic #matter #core #neutron #stars