Quark Stars and how to relate to black holes

[mmaayeh]

I was reading an article in the Physics World web site (http://physicsworld.com/cws/article/news/41419) regarding Quark Stars calculation where the center of neutron stars may have a sea of quark matter since the pressures can be even greater at the center than the surface.

However, do you think that there are any indications based on these type of studies of what is at the center of a black hole? Is it a more exotic form of strange quark matter or boson matter, etc.?

[Tensor]

I was reading an article in the Physics World web site (http://physicsworld.com/cws/article/news/41419) regarding Quark Stars calculation where the center of neutron stars may have a sea of quark matter since the pressures can be even greater at the center than the surface.

However, do you think that there are any indications based on these type of studies of what is at the center of a black hole? Is it a more exotic form of strange quark matter or boson matter, etc.?

No. The quark stars are based on the Equations of State found in the center of Neutron Stars. In a black hole collapse, gravity simply overwhelms the resistance that props up a Neutron Star.

[mmaayeh]

No. The quark stars are based on the Equations of State found in the center of Neutron Stars. In a black hole collapse, gravity simply overwhelms the resistance that props up a Neutron Star.

I understand that gravity overwhelms the neutron star from maintaining itself. Can you infer degeneracy down to the sub-particle level when you have even a neutron collapsing? I assume that is why that there is a sea of quarks at the center of a neutron star. So, can you continue this logic to say that (I am not sure if this is considered accurate conceptualization but ...) gluons fall into the quark and that changes the quark into say another flavor or another type of sub atomic particle? Is this fair or there is something else entirely happening and it cannot be answered yet?

[loglo]

There was speculation about a preon (http://en.wikipedia.org/wiki/Preon), but it doesn't seem to have gone anywhere.

[mmaayeh]

There was speculation about a preon (http://en.wikipedia.org/wiki/Preon), but it doesn't seem to have gone anywhere.

Yes, I saw preon in wiki http://en.wikipedia.org/wiki/Preon

It seems like there is no composite for quarks and leptons so, that would mean that the next step would be another kind of energy state (I assume)? And, that cannot be answered right now based on the current understanding of physics.

[Tensor]

I understand that gravity overwhelms the neutron star from maintaining itself. Can you infer degeneracy down to the sub-particle level when you have even a neutron collapsing?
Not really, but some. The problem is that degeneracy pressure is based on Quantum Mechanical ideas. The smaller area a you box a fermion into, the faster it moves. That movement is the degeneracy pressure. This come about from the Pauli Exclusion principle. In stars, the equations of state for electrons (white dwarf) are pretty well understood. The EOS for Neutrons (Neutron Star) aren't quite as well understood (which is why the lower mass for a Black Hole still varies). As for the EOS of quarks, even less is known, at present.


I assume that is why that there is a sea of quarks at the center of a neutron star. So, can you continue this logic to say that (I am not sure if this is considered accurate conceptualization but ...) gluons fall into the quark and that changes the quark into say another flavor or another type of sub atomic particle?

Gluons change the color, not the flavor of quarks. So gluons cannot change quarks into other particles. This causes problems with trying to calculate the degeneracy pressure. Since quarks are fermions and subject to the Pauli Exclusion principle (as are electrons, protons, and Neutrons) identical quarks can't occupy the same space. However, if a gluon come along, it changes the color and thus a quark that couldn't go into a certain point, now can, with the change of color. You can see the problems this would cause when trying to compute the EOS>



Is this fair or there is something else entirely happening and it cannot be answered yet?

As far as current thought goes, Nothing else is happening.

[mmaayeh]

Not really, but some. The problem is that degeneracy pressure is based on Quantum Mechanical ideas. The smaller area a you box a fermion into, the faster it moves. That movement is the degeneracy pressure. This come about from the Pauli Exclusion principle. In stars, the equations of state for electrons (white dwarf) are pretty well understood. The EOS for Neutrons (Neutron Star) aren't quite as well understood (which is why the lower mass for a Black Hole still varies). As for the EOS of quarks, even less is known, at present.



Gluons change the color, not the flavor of quarks. So gluons cannot change quarks into other particles. This causes problems with trying to calculate the degeneracy pressure. Since quarks are fermions and subject to the Pauli Exclusion principle (as are electrons, protons, and Neutrons) identical quarks can't occupy the same space. However, if a gluon come along, it changes the color and thus a quark that couldn't go into a certain point, now can, with the change of color. You can see the problems this would cause when trying to compute the EOS>




As far as current thought goes, Nothing else is happening.

Thank you Tensor, that was a nice break down -- that helped.

So, if I understand then, we do not know enough right now about Neutron star equations of state to infer any further. Is there a good way to try to visualize the material of a neutron star to some degree. I sort of see a white dwarf material are carbon atoms with the electrons at the lowest state and these carbon atoms packed together tightly to make up some sort of a matrix of carbon atoms (not sure if there is other elements there as well). Is it accurate to say you have the same type of matrix but with neutrons or it is more than this?

[Tensor]

Thank you Tensor, that was a nice break down -- that helped.

First of, let me correct something I said. In my last post I said:

Gluons change the color, not the flavor of quarks. So gluons cannot change quarks into other particles.

Gluons do change quarks into other types of quarks, within the same flavors. Up quarks can change to down and also the other way around.


So, if I understand then, we do not know enough right now about Neutron star equations of state to infer any further. Is there a good way to try to visualize the material of a neutron star to some degree. I sort of see a white dwarf material are carbon atoms with the electrons at the lowest state and these carbon atoms packed together tightly to make up some sort of a matrix of carbon atoms (not sure if there is other elements there as well).

Not a good way to look at it. We know enough about EOS of neutron stars to say that, except for the top meter (at most), it is made up of neutrons, not carbon atoms. Gravity overcomes the charge repulsion and squeezes the electrons into the nucleus, which produces neutrons. The problems with the Neutron Star EOS is that General Relativistic effects can no longer be ignored. This complicates the calculations and as such, although we know that all Neutron star EOS show that the star is converted into almost all neutrons , we don't know by how much the compression is exactly and there is a difference in different EOS models as far as the size of the Neutron Stars.

Now the pressure in the center of the neutron star, can possible produce quark matter. It can also be that some gravitational collapses form quark stars. Again, our understanding of the EOS of quark matter is incomplete(or more accurately, the variables that go into the calculation of the EOS of quark matter (which again includes General Relativity considerations) make the calculation very problematic.


Is it accurate to say you have the same type of matrix but with neutrons or it is more than this?

I'm not sure what you mean by this.

[trinitree88]

Gluons change quark color charge....chromodynamics. W particles, the W+, and the W- are emitted by a quark as it changes flavor. This is a weak interaction, not chromodynamics.