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Posted by: Myran Nov 23 2006, 08:50 PM

For a long time there have been something of a mystery where the most energetic high energy particles originates. It have been suspected that supernova explosions were involved somehow, but other explanations have been suggested including they were somehow produced by our own galaxy or more outlandish, such as that they might have originated elsewhere than our own galaxy.
But the cosmic rays sometimes had energies even higher than what a supernova would be able to produce.

Or to put in other words, we knew about the bullet but lacked the weapon for our investigation.
Now we might have one explanation that tells us it was the butler after all.... sorry make that supernova.

http://spaceflightnow.com/news/n0611/15pinball/

Posted by: nprev Nov 24 2006, 01:43 AM

Interesting.

I wonder how well hypothetical "hypernovae" would work as extremely high-energy cosmic ray generators. From what I gather, it's thought that most of the blast energy is channeled along the star's magnetic poles; wonder if the same effect would work along a basically conical wavefront.

Posted by: deglr6328 Nov 24 2006, 03:20 AM

That was interesting but all the articles, even the chandra website, are so "laymanized" that I can't really even tell how they did what they did! So I hunted down the article and found that it was published first http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0608/0608401.pdf if anyone is interested. So far as I can see, it explains super-high cosmic ray energies up to the so called Bohm limit (apparently a limit of shock scattering type particle acceleration) but this limit only goes up to 3 EeV (10^18 eV) . So it may explain the http://imagine.gsfc.nasa.gov/docs/features/topics/snr_group/cr-knee.html past the "knee" at the PeV range and possibly into the "ankle" region at the low EeV range but so far as I can see it still does not explain how ULTRAHIGH-energy cosmic rays can exist past the so called GZK cutoff in the 10^19 eV range where the blueshift of the cosmic microwave background is so intense that the high energy particles start compton scattering off of it at galactic distances. ie. it does not explain the nearly ZeV energy "oh-my-god particles". Am I understanding this right? Someone correct me if I'm wrong!

Posted by: Myran Nov 24 2006, 02:41 PM

You are correct, this doesnt explain the ultra high energy cosmic rays, on the other hand those are a once in a lifetime event hitting anyones detector.
We still need one outlandish and perhaps extragalactic explanation for those very rare ones of the highest energy, such as cosmic strings, branes or the decay of highly exotic particles. I didnt go for scientific accuracy in my own post, since I am none.

But I will do so now and say the original post could have been improved with the title 'Galactic cosmic rays explained'.

And thank you for the link to 'Cosmic ray diffusion near the Bohn limit' - finding that one I must say you're a sleuth yourself.