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More evidence for quarks at the centers of massive neutron stars

A new theoretical analysis puts the probability that massive neutron stars hide quark nuclei within them at a rate of between 80 and 90 percent

Artist's impression of the different layers inside a massive neutron star, with the red circle representing a large quark-matter core. Credit Jyrki Hokkanen, CSC
Artist's impression of the different layers inside a massive neutron star, with the red circle representing a large quark-matter core. Credit Jyrki Hokkanen, CSC

Neutron star nuclei contain the highest density of material observed in our current universe, with up to two solar masses of material packed into a sphere 25 kilometers in diameter. These objects can be seen as giant atomic nuclei, with gravity compressing their nuclei to a density far exceeding that of individual protons and neutrons.

This density makes neutron stars interesting astrophysical objects from the point of view of nuclear particle physics. A long-standing open problem concerns the question of whether the enormous pressure at the center of neutron stars can compress protons and neutrons into a new material, known as cold quark matter. In this exotic state, protons and neutrons no longer exist.

"Instead, the quarks and the gluons that make them up are released from their "prison" and begin to move almost freely," explains Alexi Vorinen, professor of theoretical particle physics at the University of Helsinki.

In a new paper recently published in Nature Communications, the researchers provided the first-ever quantitative estimate of the likelihood of quark nuclei in the centers of massive neutron stars. They showed that, based on current astrophysical observations, quark matter is almost inevitable in the most massive neutron stars: a quantitative estimate the team reproduced put the likelihood in the 80-90 percent range.

The small remaining probability that all neutron stars are composed of only nuclear matter requires that the change from nuclear matter to quark matter be a strong first-stage transition, somewhat similar to that of liquid water turning to ice. This kind of change in the properties of the neutron star material has the potential to make the star so unstable that the formation of even a tiny quark nucleus would cause the star to collapse into a black hole.

The international collaboration between scientists from Finland, Norway, Germany and the USA was able to further show how the existence of quark nuclei may one day be verified or rejected. The key is to be able to constrain the strength of the phase transition between nuclear matter and quark matter, expected to be possible when a gravitational wave signal from the last part of a neutron star merger is detected by the gravitational wave detector.

Huge computer runs using observational data

In the current study, the researchers used Bayesian inference (the idea that the likelihood of a given hypothesis varies depending on the observational data) on a huge data set run on supercomputers to calculate the likelihood that massive neutron stars contain quark nuclei. They did this by comparing their theoretical predictions with observational data of neutron stars.

The results showed that the researchers' theoretical predictions fit well with the observational data when it is assumed that quarks exist in the centers of the most massive neutron stars.

Implications of the study

The present study provides further evidence that quarks may exist in the centers of massive neutron stars. If these results are confirmed by further research, they will have significant implications for nuclear particle physics.

If its existence is confirmed, quark matter would be a new phase of matter expected to exist under conditions of very high density. They will also provide new information about the properties of quarks, which can be used to test theoretical models of particle physics.

The researchers continue to investigate the issue, and hope that one day they will be able to confirm the existence of quark nuclei definitively.

for the scientific article

More of the topic in Hayadan:

10 תגובות

  1. Muti - there is a physical law that acts on particles of matter and is called "Pauli's exclusion principle". This principle prevents particles of matter from getting too close to each other.
    In neutron stars, gravity is not strong enough to break the principle. Black guys do.
    All neutron stars have a limit to how much matter can compress and a black hole has no limit.

  2. Enough with these Foggy stories!!! The deepest they've been able to drill here on our planet is about 8 kilometers and they don't really know what's next, they only "guess" 🤪🤪 and here too they make sure to write down a "new theoretical analysis" lol
    Working on us!!

  3. It seems that the article was translated by Google Translate and Adam did not go over the translation

  4. The study claims that the force of gravity overcomes the nuclear forces. So what is the difference between a neutron star and a black hole?

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