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The core of some neutron stars is made of free quarks – 2024-03-30 05:46:41

2024-03-30 05:46:41

The cores of neutron stars contain what can still be considered matter as we understand it, albeit at the highest densities achieved in our current universe, with up to two solar masses of matter compressed within a sphere 25 kilometers in diameter.

Beyond this level of density, a black hole is created, from which nothing, not even light, can leave, and which raises many unknowns about the nature of what is inside.

In more ways than one, neutron stars can be considered giant atomic nuclei. In fact, gravity compresses matter in them to densities that far exceed those of individual protons and neutrons.

These densities make neutron stars objects of great interest for particle physics. A long-overdue mystery is whether the immense central pressure of neutron stars can compress protons and neutrons into an exotic phase of matter, known as cold quark matter. In this exotic state of matter, individual protons and neutrons no longer exist. On the other hand, the quarks and gluons that compose them are freed from their typical confinement and can move almost freely.

An international team including Eemeli Annala and Aleksi Vuorinen of the University of Helsinki in Finland, among others, has provided for the first time a quantitative estimate of the probability that neutron star nuclei made mostly of quark matter exist.

The authors of the study have shown that, based on current astrophysical observations, quark matter is almost inevitable in the cores of the most massive neutron stars. The quantitative estimate places the probability between 80 and 90 percent. This result has been arrived at through extensive supercomputer calculations.

The remaining small probability (10-20%) that all neutron stars are composed solely of matter based on atomic nuclei (essentially neutrons) requires that the change from nuclear matter to quark matter be a first-class phase transition. order, similar to that of liquid water turning into ice.

This type of rapid change in the properties of a neutron star’s matter could destabilize the star such that the formation of a core of quark matter, however tiny, would cause the star to collapse into a hole. black. There would then be no stars with quark nuclei because they would immediately become black holes.

Fuente: : NCYT de Amazings

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