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Can matter focus neutrinos in a supernova event?

by Spinnor
Tags: event, focus, matter, neutrinos, supernova
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Spinnor
#1
Feb17-13, 01:14 PM
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The initial flux of neutrinos from a supernova is mostly radial (say we are far from where they are produced but also far below the top of the dying star)? As the neutrinos help blow the top off the star do the density variations of the outer portions of the star act like a variable index of refraction and cause focusing of the radial neutrino flux? If so what might typical focusing power be 2X, 20X, ... times the average flux?

Does the neutrino flux cause an electrical polarization of the expelled outer layers of the star, if so what might the maximum electrical fields be? If this polarization relaxes can we expect electromagnetic radiation?

Thanks for any help!
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mathman
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Feb17-13, 03:36 PM
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I haven't made any quantitiative analysis. However neutrinos react very weakly with matter so I doubt if there is any such effect as you described.
Chronos
#3
Feb17-13, 09:01 PM
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Neutrinos have no charge and hardly interact with the outer layers of the star during a core collapse event.

Spinnor
#4
Feb18-13, 06:35 AM
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Can matter focus neutrinos in a supernova event?

Quote Quote by Chronos View Post
Neutrinos have no charge and hardly interact with the outer layers of the star during a core collapse event.
I realize the effect may be very small but reading the following I was under the impression that it was the neutrinos that were responcible for blowing off the top of the star? I'm guessing there should be a back of the envelope calculation for an estimate for this effect. I have the envolope and pen but not sure how to proceed.

http://www.astrophysicsspectator.com...eCollapse.html

"When a stellar core collapses, its high density spurs the creation of thermal neutrinos through a variety of processes. The core itself is not transparent to neutrinos, so they interact and come into thermal equilibrium with the core before escaping. The mass surrounding the core is almost transparent to these neutrinos, so very few neutrinos give up energy to the surrounding mass. The tiny amount of energy lost by the neutrinos to the surrounding mass, however, is more than sufficient to blow this mass away from the core. The most energetic explosions in the universe therefore hide most of their energy from our sight; we see the brilliant light and the high speed of the supernova debris, but we almost never see the neutrinos that carry away almost all of the energy generated in the birth of the neutron star. ...

In particular from the above,

"The mass surrounding the core is almost transparent to these neutrinos, so very few neutrinos give up energy to the surrounding mass. The tiny amount of energy lost by the neutrinos to the surrounding mass, however, is more than sufficient to blow this mass away from the core."

If true the outer layers are given a tremendous kick and it seemed that the kick would not be symmetric between the light electron and the heavier positively charged nuclei?
Chronos
#5
Feb18-13, 09:29 AM
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The neutrinos we receive are the ones that did not give up their energy to the outer envelope, so, I can think of no reason they would be refracted. We know, however, almost nothing about their distribution. We only detect a handful of neutrinos from any given supernova explosion [they don't give up energy to our detectors any easier than they do to the outer envelope]. Supernova explosions are, however, assymetric. See 'Neutron Star Kicks and Supernova Asymmetry', for discussion.


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