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Shape of quark matter bubble in a magnetized neutron star

  1. Dec 15, 2015 #1
    If a bubble of quark type matter formed near the core of a magnetized neutron star, what would happen to its shape? Would it elongate along the magnetic field lines? Could it burst out of the magnetic poles of the star?
     
  2. jcsd
  3. Dec 15, 2015 #2
    'Quark matter' implies that the neutron star is at least in part degenerating into free quarks.
    We don't yet know if it's possible for a neutron star to collapse further becoming a hypothetical quark star, (if for instance two neutron stars are merging.)
    The alternative scenario for such a further collapse leads directly to a black hole with there being no such intermediate state.
    As far as I know there have been no observations of objects that might be quark stars, whereas many neutron stars have been identified, and plenty of black hole candidates too.
     
    Last edited: Dec 15, 2015
  4. Dec 15, 2015 #3
    I'm not suggesting a neutron star is a quark star. What would happen to a bubble of ultra relativistic charged particles in the core of a neutron star?
     
  5. Dec 15, 2015 #4

    fresh_42

    Staff: Mentor

    But if you're not talking about a quark-gluon-plasma, then those "bubbles" are simply accelerated protons and neutrons, aren't they?
     
  6. Dec 15, 2015 #5
    Rephrase my question: What would happen to a bubble of quark-gluon-plasma near the core of a magnetized neutron star?
     
  7. Dec 15, 2015 #6
    Consider a hypothetical spherical bubble of quark-gluon-plasma near the core of a magnetized neutron star: Would the bubble elongate along the magnetic field lines or would it remain spherical?
     
  8. Dec 15, 2015 #7
    It would decay, and quickly. A neutron star doesn't have the pressure or heat required for quark-gluon plasma to be stable, even at it's core.
     
  9. Dec 15, 2015 #8

    Wouldn’t the radiation and quark type matter in the bubble bounce off the surrounding neutrons for many bounces as the bubble decayed? While decaying shouldn’t the bubble elongate? Would the bubble even be briefly explosive along the magnetic axis? My guestimate is a 2 SM neutron star reaches a gravitational core pressure of ρc2/3 at about 12-km, so shouldn’t core neutrons start to collapse at about this point? If some of the core changed from charge neutral neutrons to ultra relativistic charged particles, could this plasma exit the star along the magnetic axis like plasma escaping a solenoid, either continuously or in bursts?
     
  10. Dec 16, 2015 #9
    While this doesn't include any magnetic field a neutron star might have, you might find this article of interest-

    The Strange Insides of Neutron Stars
    http://www2.lbl.gov/Science-Articles/Archive/sb/Nov-2004/03-neutron-stars.html
    '..where hadronic matter and quark matter are mixed, if quark matter is in the minority the quarks are segregated as droplets in a crystalline array, each droplet at a lattice point. As the pressure increases the proportion of quark matter increases and the droplets elongate to rods; still more pressure means still more free quarks, and the rods join into slabs.
    As pressure continues to increase, quark matter becomes the dominant phase, and the hadrons inside it form slabs, rods, and finally droplets, just before the system turns to pure quark matter. (this is) jokingly referred to as a pasta model: "Drops like orzo, rods like spaghetti, slabs like lasagna".'
     
  11. Dec 16, 2015 #10
    Thanks for the great link which has led to other good links. Norman Glendenning is my new reading for relativistic stars.

    For this thread I was thinking that instead of stationary quarks in a neutron star core there could be hot ultra-relativistic quark matter there.

    Could the jets from a magnetized neutron star be caused by neutrons in the core collapsing into ultra relativistic quark matter that escapes out of both ends of a solenoid?
     
  12. Dec 17, 2015 #11
    I think your logic is that if a hot bubble of quark-gluon plasma formed at the core of a neutron star, it would decay almost instantly by losing its heat to the much lower temperature medium surrounding it. If so that makes sense but what if this bubble ejected plasma along its magnetic axis while the bubble was being fed by the collapsing neutrons around it? Could it be a stable structure as long as the bubble was fed?
     
  13. Dec 20, 2015 #12
    As of now, we have quite limited knowledge of properties of "quark-gluon-plasma" to give meaningful predictions.
     
  14. Dec 20, 2015 #13
    We know that IF neutral neutrons collapse to hot charged quark matter that the hot charged quark matter should be affected by a magnetic field.
     
  15. Dec 20, 2015 #14
    Consider a magnetic cannon open on both ends and fed from the center by quark type matter. Would it be stable or collapse or explode? It has a path of pressure release. The rate of feed at the core should be limited by the core magnetic field and available fuel. Hence the ejection rate and barrel diameter would be limited. Isn't that a stable structure? It would be expected to shoot interesting stuff from both ends.
     
  16. Dec 21, 2015 #15
    That's not a particularly large amount of knowledge. Of course quars are affected by magnetic fields, they are electrically charged. But quarks also interact via color forces, they are much stronger than electromagnetism, but have peculiar properties such as asymptotic freedom.

    Whether magnetic field interactions would have a significant effect depends on how exactly quark plasma color interactions cancel out, or not. We are far from being able to quantitatively predict that.

    That's what I mean by "we have quite limited knowledge of properties of quark-gluon-plasma".
     
  17. Dec 21, 2015 #16
    While it's not necessarily hard science yet, it's certainly being considered (note, the quark matter doesn't escape but the energy released during the transformation might)-

    Gamma Ray Bursts from delayed collapse of neutron stars to quark matter stars
    http://arxiv.org/abs/astro-ph/0209257
     
  18. Dec 21, 2015 #17
    Would hot quark matter in this hypothetical magnetic cannon recombine into protons and electrons before exiting the surface of the star or would a significant amount of hot quark matter exit the star? I don’t know.
     
  19. Dec 21, 2015 #18
    That sounds correct for a non-magnetized core. Here's my guess for a non-magnetized core: Collapsed mass at the core probably just heats the star, but what an enormous amount of heat. If core collapse directly converts 1/10,000 of a neutron star's mass to heat, thats like adding 100,000 eV of heat to a proton, or 10^9 degrees K. The neutron star would get so hot it should radiate all the 1/10,000 mass as heat. I think the heat from collapse in the core could be much greater than heat from surface fusion reactions of accreting hydrogen. Could this radiated heat (originating from collapse in the core) be the main process that limits the mass of non-magnetized neutron stars? It seems weird.
     
  20. Dec 22, 2015 #19
    Your numbers look off - they are too low! :)

    Core-collapse supernova's core _starts_ with temperature of 10^9 K (or more) before collapse: neon burning starts at 1.6 gigakelvins. Oxygen burning is even hotter.

    NS has a mass deficit not of 1/10000, but ~20% (!!!) due to gravitational binding energy. For one solar mass, that would be 3.6*10^46 joules.

    I believe current simulations predict that immediately after collapse, freshly created NS has temperatures from 100 to 1000 GK. At 100 GK, a square meter of NS surface shines with 14.7 billion solar luminosities (that's 14 billion of entire Sun's power, not the power emitted by a square meter of Sun's surface). Entire NS radiates with about 1-10*10^41 W of power.

    As enormous as it is, IIRC current understanding of NS formation indicates that electromagnetic emissions are less than 1% of NS power output - most of energy is carried away with neutrinos, not light.
     
  21. Dec 22, 2015 #20
    Thank you for that thought stimulating information. But what limits the mass of old neutron stars to about 2 solar masses? Could neutron collapse occur in the core? Do old neutron stars emit neutrinos? I read that just the formation of neutrons results in neutrinos, but that doesn't explain the mass limitation. Could collapse of neutrons at the core of an old neutron star release energy that would (1) diffuse thru the star and heat the entire star? (2) escape out the magnetic poles? (3) something else?
     
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