Sunday, 16 August 2015

Neutrinos arrived before the photons (supernova)


A while back I read about the super Kamiokande detector detected a large neutrino flux and then several hours later a supernova was seen. Anyone know of this with sources? I don't recall the source at the moment.



Answer



http://profmattstrassler.com/2011/09/20/supernovas-and-neutrinos/



This website confirms what you said about the neutrinos from the 1987 supernova arriving before the light from the supernova. It doesn't specifically say which detectors detected the neutrinos.


The reason the neutrinos reached earth before the light is not because the neutrinos were travelling faster than light but because they were travelling about as fast as light but were able to escape the star before the shock waves from the supernova explosion (and the subsequent release of light) reached the surface of the star, because neutrinos are able to pass through matter basically unimpeded but the shock waves and photons were interacting with the matter of the star all the way out.


It is worth noting though that the scientists working at Kamiokande didn't look for the neutrinos from before the supernova until the actual supernova was discovered from its electromagnetic emission; thus, although the neutrinos came before the light, nobody noticed until after the fact.


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