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Bernie G
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Could accreting material on a neutron star’s poles impact with enough energy to initiate fusion reactions, some of which escapes the star as ultra-relativistic jets?
Bernie G said:Sorry to post so much, maybe the above thoughts explain little.
Do charged particles from fusion reactions even have sufficient energy to escape the surface of a 2 SM neutron star? My guess is no. If so, would whatever escapes a neutron star's surface have to have an ultra-relativistic source? If there is an ultra-relativistic source what choices are there for its location?: (1) above the star surface? (2) at the star surface? (3) on a plateau above the surface? (4) below the surface? (5) the core?
I think ultra-relativistic conditions could exist at the core. Not so sure about the other places.
Jonathan Scott said:It is already assumed that X-ray bursts from neutron stars are caused by material falling onto the surface and immediately undergoing fusion because of the impact energy.
Jets are not yet fully understood, but quasars also have jets and are thought to involve black holes rather than neutron stars, so the same explanation could not work in that case.
I've previously heard that jets are probably caused by falling ionised plasma being accelerated out of the equatorial plane towards the polar directions by twisted magnetic fields (from relativistic spinning), but then being partially neutralised (perhaps combining with free electrons or even electrons derived from pair production) so that the resulting neutral material escapes the magnetic field. I'm not up to date with recent research on the subject.
Hornbein said:Last I heard some thought that the jets were understood as an effect of general relativity, some disagreed. The jets are similar to the jets from black holes, so (1) seems like the frontrunner.
Bernie G said:That makes sense. Gravity, magnetic field, and spin combine above the neutron star's magnetic pole to cause ultra-relativistic conditions to exist. Hmmm.
Question: Would the ultra-relativistic jet above the neutron star's pole go in both directions, and pierce the surface of the star?
Hornbein said:The crust of a neutron star is very likely the strongest, toughest stuff in the universe. I can't imagine it being pierced by anything. The outer surface is ultradense polymerized iron.
Hornbein said:The crust of a neutron star is very likely the strongest, toughest stuff in the universe. I can't imagine it being pierced by anything. The outer surface is ultradense polymerized iron.
Jonathan Scott said:This idea of "ultra-relativistic matter" moving around within the core of a neutron star doesn't make sense to me. It's unbelievably dense solid material.
If it's something you invented, this is not the place to discuss it; this forum is for discussing subjects based on accepted scientific principles.
Jonathan Scott said:This idea of "ultra-relativistic matter" moving around within the core of a neutron star doesn't make sense to me. It's unbelievably dense solid material.
If it's something you invented, this is not the place to discuss it; this forum is for discussing subjects based on accepted scientific principles.
Hornbein said:The core of a neutron star is superfluid. The electrons moving about are relativistic. The core is also a proton superconductor.
Superfluids seem to me to be the same as a superconductor except with neutral particles.
There was some interest in a quark plasma inner core, but with the discovery of a 1.97 stellar mass neutron star this view has gone out of style.
Bernie G said:Yes, but what are the accepted scientific principles to describe the jets?
.Hornbein said:There was some interest in a quark plasma inner core, but with the discovery of a 1.97 stellar mass neutron star this view has gone out of style.
Jonathan Scott said:... I think that's the best answer we can give to your original question (which however mutated a bit). ... Although it is fun to discuss wildly speculative ideas, this forum is for discussions within the scope of accepted scientific principles.
Jonathan Scott said:How is your "ultra-relativistic matter" getting its energy?
I thought the core matter got its additional energy from gravity, in which case lifting it up from the core to the surface will take that energy away again.
Jonathan Scott said:I do not recall having heard of any energy source which could result in a "bubble" or anything else moving at relativistic average speed over macroscopic distances through this material.
Collider experiments show that when a nuclei disintegrates it results in roughly 10% quark type matter and 90% energy. If neutron collapse happens something like this should be expected. A bubble of this stuff would displace neutrons.Jonathan Scott said:How is your "ultra-relativistic matter" getting its energy?
Regardless of what you do to a neutron, baryon number conservation means that the bits must have at least enough rest mass to create a proton (and an electron), which is barely less than the original neutron rest mass. So the amount of additional kinetic energy is negligible. For a collider, the incoming particles already had the energy.Bernie G said:Collider experiments show that when a nuclei disintegrates it results in roughly 10% quark type matter and 90% energy. If neutron collapse happens something like this should be expected. A bubble of this stuff would displace neutrons.
Jonathan Scott said:Regardless of what you do to a neutron, baryon number conservation means that the bits must have at least enough rest mass to create a proton (and an electron), which is barely less than the original neutron rest mass. So the amount of additional kinetic energy is negligible. For a collider, the incoming particles already had the energy.
Jonathan Scott said:Gravitational energy gives the particles in the core so much kinetic energy that their speeds are relativistic, corresponding to incredible temperatures. If you move any of that matter back up to the surface, it will simply lose the corresponding amount of energy so that it will match the kinetic energy of the surface material (which is still pretty incredible). Fusion reactions allow you to convert a bit of rest mass into kinetic energy, and so does neutron decay to a proton, but the relative amounts of energy in both cases are still small compared with the gravitational energy lost through falling onto a neutron star.
What's this about "ultra-relativistic matter" being generated anyway? If material falling towards a neutron star is caught up in an accretion disk, being sped up by angular momentum conservation, then deflected away towards the poles and given a little extra energy, for example by rotating twisted magnetic fields (which cause an induced electric field effect), then it will have more than enough energy to escape at a relativistic speed. In contrast, I can not think of anything that could happen at the surface which could propel any massive particle back into space.
That gravitational energy is much more energy per particle than could be released by fusion. Rather than anything arising from the surface, it is energetically far more likely that the material heading away from the poles is a fraction of the infalling gas, which already has acquired the kinetic energy from falling, and would only need relatively minor electromagnetic acceleration to escape again. As I've mentioned before, the exact mechanism of that acceleration is not understood, but it is thought to be related to the electromagnetic field of the neutron star being twisted by relativistic delay effects.Bernie G said:For an infalling particle the maximum gravitational potential energy that it could gain outside a black hole is 0.5mc^2 (I think). The gravitational potential energy outside a neutron star is even less. Gravity outside a neutron star and even a black hole just isn't strong enough to directly accelerate a particle to ultra-relativistic velocities. Electrons in an accreting disk should be at least relativistic but the ions which are the vast bulk of the disk not nearly so much. In your model of accretion disk material exiting the magnetic poles, why does it all head away from the star instead of heading towards the star?
Jonathan Scott said:As I've mentioned before, the exact mechanism of that acceleration is not understood, but it is thought to be related to the electromagnetic field of the neutron star being twisted by relativistic delay effects.
http://www.astronomy.com/news/2015/08/neutron-stars-strike-back-at-black-holes-in-jet-contestJonathan Scott said:I've not seen the suggestion that accretion and jet activity do not occur at the same time.
OK, I see what you mean. I had interpreted that as a mismatch of strengths, but it does involve timing too.Bernie G said:
I don't know what your "ultra-relativistic matter" is meant to be if it isn't simply the same stuff under more pressure. And I don't know the mechanical properties predicted for the hypothetical quark gluon plasma.Bernie G said:Lets use symbol for URM for ultra-relativistic matter or quark gluon equivalent. What would happen to a star that was a mixture of neutrons and URM?
If you mean SR = Solar Radius, you're very confused, as the radius of a neutron star is about 35,000 times smaller than the sun.Bernie G said:Would it regulate its radius to 1.00 SR?
Suggestion: SR = Schwarzschild radius. SM = solar mass. URM = ultra-relativistic matter. NS = neutron star.Jonathan Scott said:OK, I see what you mean. I had interpreted that as a mismatch of strengths, but it does involve timing too.
I don't know what your "ultra-relativistic matter" is meant to be if it isn't simply the same stuff under more pressure. And I don't know the mechanical properties predicted for the hypothetical quark gluon plasma. If you mean SR = Solar Radius, you're very confused, as the radius of a neutron star is about 35,000 times smaller than the sun.