3 ms·

Um... is there any trace of neutrino bursts before that? Im not sure anyone bothered checking, since such a correlation would have been very hard to justify. A

Um... is there any trace of neutrino bursts before that? Im not sure anyone bothered checking, since such a correlation would have been very hard to justify. A neutrino burst 4 years before a supernova... so what? Could a physicist clarify whether neutrinos could travel at different speeds in vacuum like any 'normal' particle, or are 'fixed speed' like photons. We could well have had several waves with the bulk arriving at c-epsilon and no one bothering to check outside the expected time frame.

lutorm 15y ago
Well, the point is that there was a neutrino burst coincident with SN87a. So if there was one 4yr earlier, too, then you'd have to explain how the same event produced two bursts of neutrinos with different speeds, while within the burst they apparently had exactly the same speed. If neutrinos have mass, they can travel at any speed <c depending on their energy, like any other massive particle. Of course, the upper mass limit is quite low, so even with very little energy they will go very fast. (Edit: In fact, the arrival interval of those neutrinos puts an upper limit on the neutrino mass, because the larger the mass, the more different the speed and the more dispersed the arrival of them at Earth.)
- nickolai 15y ago
  I'm no physicist, so I am just guessing. It could be some phenomenon similar to what we see in emission spectrums, where a pure source can emit photons at multiple precise energy levels. except that in the case of particles with mass(apparently neutrinos have a mass) this would result in a difference in speed. Not a big enough difference to be noticed on 700 km , but enough to make a 4 yr difference on 170kly. Of course this is still wild speculation without much background.
  - lutorm 15y ago
    Neutrinos released in type II supernova explosions are thermal, so they should have a broad spectrum unless pretty much everything we think we know about SNe is wrong.
- kpanghmc 15y ago
  Maybe the neutrinos that appeared 3 hours before the event are from another event altogether (one that occurred even further away, whose light particles haven't even reached us yet)?
  - lutorm 15y ago
    Given that the flux goes as 1/r^2, and the sum total of the neutrinos detected in association with 87a was something like 17, a SN in any external galaxy would be undetectable.

lutorm 15y ago

Well, the point is that there was a neutrino burst coincident with SN87a. So if there was one 4yr earlier, too, then you'd have to explain how the same event produced two bursts of neutrinos with different speeds, while within the burst they apparently had exactly the same speed. If neutrinos have mass, they can travel at any speed <c depending on their energy, like any other massive particle. Of course, the upper mass limit is quite low, so even with very little energy they will go very fast. (Edit: In fact, the arrival interval of those neutrinos puts an upper limit on the neutrino mass, because the larger the mass, the more different the speed and the more dispersed the arrival of them at Earth.)

nickolai 15y ago
I'm no physicist, so I am just guessing. It could be some phenomenon similar to what we see in emission spectrums, where a pure source can emit photons at multiple precise energy levels. except that in the case of particles with mass(apparently neutrinos have a mass) this would result in a difference in speed. Not a big enough difference to be noticed on 700 km , but enough to make a 4 yr difference on 170kly. Of course this is still wild speculation without much background.
- lutorm 15y ago
  Neutrinos released in type II supernova explosions are thermal, so they should have a broad spectrum unless pretty much everything we think we know about SNe is wrong.
kpanghmc 15y ago
Maybe the neutrinos that appeared 3 hours before the event are from another event altogether (one that occurred even further away, whose light particles haven't even reached us yet)?
- lutorm 15y ago
  Given that the flux goes as 1/r^2, and the sum total of the neutrinos detected in association with 87a was something like 17, a SN in any external galaxy would be undetectable.