[queuebert]

It's worth noting that we received the neutrinos from Supernova 1987a before the photons. We think that's because the photons have a difficult time escaping the ejecta cloud, while neutrinos stream away freely, but who knows ...

[PaulHoule]

Oddly another detector caught a burst of low energy neutrinos that came a few hours before the burst that everyone accepts was from 1987a

https://www.sciencedirect.com/science/article/pii/S092765051...

Low energy tachyons would go a little faster, but you've got the additional problem of explaining why neutrinos got emitted in a spectral line.

[queuebert]

That is weird. Is the conventional explanation a flash from one of the last fusion stages right before core collapse?

[PaulHoule]

The core collapse itself produces most of the neutrinos. All of these protons are squeezed together with electrons which produces neutrons and neutrinos.

[queuebert]

I was referring to the earlier monoenergetic flash. Yes, most should be produced through electron capture in the collapse, but for earlier event to be monoenergetic suggests a specific nuclear process to me.