I understand the certain phenomenon even in other galaxies, such as supernovas, produce neutrinos that we can detect back here on Earth. I have also heard that we have experimental methods that can distinguish neutrinos and antineutrinos, at least under some conditions. Finally, I hear that one reason we think there is missing antimatter in the universe is that we don't see evidence of some galaxies being matter and others being antimatter.

Two of the types of evidence you'd expect would be energy from interactions when galaxies and antigalaxies collide and the other evidence would be the aforementioned supernova emitting antineutrinos instead. I understand that we haven't seen evidence of the former but I'm curious if we've actually looked at extra-galactic neutrino sources using methods that would distinguish them from their antiparticle and what our results were.

If these experiments haven't been done, do we know how close we are to being able to perform them or if other indirect methods can rule out various sources as being antimatter?

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    $\begingroup$ I believe that we have a sum total—across all experiment, all techniques, all decades—of a few dozen neutrino events that can be confidently linked to a particular extra-galactic event (all for sn1987a). $\endgroup$ Apr 10, 2018 at 7:16
  • $\begingroup$ That's interesting. So we maybe only have experimental evidence of this kind that one other galaxy is matter rather than antimatter. $\endgroup$ Apr 10, 2018 at 13:49
  • $\begingroup$ Has IceCube linked any of its observations to extragalactic sources? $\endgroup$ Apr 18, 2018 at 14:03


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