Do neutron stars have quark cores?

   Do neutron stars have quark cores? 

"New theoretical analysis places the likelihood of massive neutron stars hiding cores of deconfined quark matter between 80 and 90 percent. The result was reached through massive supercomputer runs utilizing Bayesian statistical inference." (ScitechDaily.com/Neutron Stars’ Inner Mysteries: A Glimpse Into Quark-Matter Cores)

Neutron star's inner cores might involve quark cores. That means there could be also quark stars in the universe. Theoretical models made at the University of Helsinki support the possibility that heavy neutron stars are quark cores. That thing opens a very interesting vision for gravitation and star research. In theoretical models, Magnetars are very light neutron stars. Which shell rotates very fast around its structure. That forms a very strong magnetic field. 

In heavy neutron stars. Gravity locks structure into its entirety. And that makes those heavy neutron stars' magnetic fields weaker but their gravity fields are stronger. That means gravity seems acting like some kind of membrane or strings. That travels between or through neutrons. And that locks the structure into one piece. 

"Artist’s impression of the different layers inside a massive neutron star, with the red circle representing a sizable quark-matter core. Credit: Jyrki Hokkanen, CSC" (ScitechDaily.com/Neutron Stars’ Inner Mysteries: A Glimpse Into Quark-Matter Cores)

Hypothetical quark star: an object intermediate. Between neutron stars and black holes.

We can think that the quark star is an object intermediate between neutron stars and black holes. Nobody has seen that thin yet, so it's a theoretical object. 

The mass of neutron stars determines their quark core's size. And in light neutron stars might not be quark core. Then there would be no quark core or a very small quark core in magnetars. But the part of the pure quark structure in neutron stars rises when their mass rises. And when a collapsing star's mass is high enough all neutrons turn into quarks and form a quark star. 

But then we can continue this thinking game. The idea is that the model can also be in white dwarfs and black holes. So in a very heavy white dwarfs could be neutron stars inside them. In a very heavy quark stars could be back holes in the free quark structure. 

The quark star forms when a neutron star turns too heavy that neutrons can keep their shells. The extreme gravity along with neutron radiation, strips those quantum fields away from the neutrons. That uncovers quarks. And the quark stars would be much denser than neutron stars. Those quarks send their radiation in the wavelength that is the same as the quark's dimension. And that thing could make the quark star almost invisible. 

The quark structure would be far stronger than the neutron structure. That means inside the heaviest quark structures can form a black hole or area where even light cannot escape. And in that model is possible. That those quarks form a symmetrical quark net around that black hole. That quark net could keep that structure in its form. 

In some models, there is the possibility that also gluons can form structures that are similar to quarks. Those gluon stars are hypothetical things, and they are very close to black holes. In some models when a hypothetical quark star massive gravity pushes those quarks so close to each other. That they will push gluons out from that structure. In that model, the quark stars are the only things between black holes and neutron stars. 

Is there gluon stars?

If a quark star exists, is it possible that gluon stars also exist? Gluon is not fermion. But it's a near possible limit that massive gravity and radiation pressure in a supernova form black hole there is a network of gluons near its event horizon. Gluons are gauge bosons. But a black hole's strong gravity and energy load locks those gluons into position making them interact like quarks that are fermions. 

In some other models intensive pressure and heat in high-mass quark stars can form structures where is only quark-gluon or gluon plasma. That kind of structure is a hypothetical thing. 

https://physicsworld.com/a/calculations-point-to-massive-quark-stars/

https://scitechdaily.com/neutron-stars-inner-mysteries-a-glimpse-into-quark-matter-cores/

https://en.wikipedia.org/wiki/Quark_star