There is something unimaginable inside a neutron star. There is new evidence

We can be sure of one thing. The interiors of neutron stars are made of the densest material in the universe. So it's not surprising that scientists often talk about neutron stars as giant atomic nuclei, the density of which is many times higher than that of individual protons or neutrons.

It is therefore not surprising that the interiors of massive neutron stars are extremely interesting to both astronomers and physicists who deal with elementary particles on a daily basis. The enormous pressure prevailing at the center of such a star could theoretically cause protons and neutrons to transform into an entirely new phase of matter, combining with each other in so-called cold quark matter in which individual particles no longer exist. Everything indicates that in such a state of matter, the quarks and gluons components lose their boundaries and move almost freely within the matter.

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A team of scientists from the University of Helsinki He recently attempted to measure the probability of the existence of cold quark nuclei inside massive neutron stars. In the course of their research, the researchers determined that the presence of quark matter is almost certain in the most massive neutron stars. The probability of its presence has been determined to be 80-90 percent.

But if it's not 100 percent, what's the alternative? Scientists acknowledge that there is a possibility that all stars are made of nuclear matter, and when even a little quark matter appears, the star is destabilized and collapses into a black hole.

Researchers point out that determining facts, contrary to appearances, is possible remotely. It will be necessary to determine the strength limits of the phase transition from nuclear matter to quark matter. In theory, this should be possible if we can record gravitational waves emitted in the final stage of the merger of two neutron stars.

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To make the estimates, scientists used a huge database of supercomputer calculations using Bayesian inference, where the probabilities of different model parameters are inferred through direct comparison with observational data. Thus it became possible to set new limits on the properties of the matter that makes up neutron stars.

Scientists admit that each subsequent observation of a neutron star allows us to more precisely determine the properties of an entire class of such objects. A million supercomputer processing hours were necessary to compare theoretical predictions with observations, thus setting limits on the possibility of nuclei made of quark matter. As you can see, it has paid off.