Comment by ziddoap

Ars Technica has an article, as well, with some additional context/explanation.

https://arstechnica.com/science/2025/02/most-energetic-neutr...

And an interesting, somewhat related, video from PBS Space Time exploring how supernovas act as particle accelerators (but don't quite explain particles like this one or the 'Oh My God' particle):

https://www.youtube.com/watch?v=2sSNWIJbV3Q