High-Energy Cosmic Ray Sources Get Mapped Out For the First Time

DesertNomad writes: A dull, dark, otherwise unremarkable spot near the constellation Canis Major appears to be the locus of extra-galactic, super-high-energy cosmic ray production, with the actual source in the Virgo cluster and the cosmic rays' paths distorted by the complex galactic magnetic field. Astrophysicists crafted the most state-of-the-art model of the Milky Way's magnetic field, and found that this model explains the significant change in direction of the cosmic rays. The findings appear in a paper via arXiv.

I miss story tags

[Powercntrl]

This one would certainly have been tagged with "spacefart". Oh, for the good ol' days [slashdot.org].

Just to clarify,

[h33t l4x0r]

These are the Fantastic Four ones. The Hulk ones are Gamma rays.

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[burtosis]

After the accident:
Billy: So now I have super powers?!?
Doc: No Billy, you have cancer.

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[sabbede]

And that's what makes this so exciting!

D i d Y o u K n o w C o s m i c R a y s C a n E n l a r g e Y o u r P e n i s T o d a y?

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[BeerFartMoron]

Pros: Rock hard. Cons: Rather rough, Orange color.

Now that it is on Slashdot...

[LordHighExecutioner]

...they will aim better their cosmic-ray gun against us!!!!

Me Admit

[boudie2]

Cosmic rays? They're over my head. We live in a complicated universe, most of which we don't understand. Why make life more complicated than it is?

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[burtosis]

Not only are they over my head, the particles they produce go right through it too.

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[boudie2]

Can't see that making you any smarter.

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[burtosis]

Can't see that making you any smarter.

Obviously you under appreciate comic book medical theory.

Cosmic Rays and More

[Roger W Moore]

Cosmic rays are high energy protons and other nuclei which plough into the atmosphere creating showers of particles some of which, mainly muons (a heavy cousin of the electron), reach the ground. The Pierre Auger Observatory detects these using tanks of water. When the particle passes through the tank it is travelling faster than light in water (this is slower than light in a vacuum which is the universe's fundamental speed limit) and so leaves a light shockwave called Cherenkov radiation that can be seen by light detectors.

Nobody really knows the origin of the extremely high energy rays. These are rays with energies many orders of magnitude higher than protons in the LHC at CERN. The reason is that the galactic magnetic fields bend the paths of charged particles. This paper attempts to use what we know of the galactic magnetic field to track the particles back from whence they came but even if we think we know the galactic magnetic field well enough to do this if the particles passed through any other magnetic fields on the way here we will have no idea where they came from.

However, there is a way to back track them using another particle often produced in association with high energy protons: neutrinos. These particles are neutral so they ignore magnetic fields and travel in straight lines but they are a lot, lot harder to detect. The experiment I work on, the IceCube Neutrino Observatory, is trying to do extactly this and we have had some success: we saw extremely high energy neutrinos that seemed to come from a blazar, a supermassive Black Hole at the centre of a galaxy that is emitting jets of high energy particles. We are looking for more sources but because it is hard to get neutrinos to interact we may need larger detectors.

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[boudie2]

I did listen to a piece on the CBC which was about the research at the Sudbury Neutrino Observatory. It was understandable what they were doing, but why seemed to be we don't know that yet.

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[DesertNomad]

Thanks for the informative post. When I read the article, I was trying to figure out how this "shower" of particles could be used to infer an inbound direction. The cosmic ray begins the process at the top of the atmosphere: the particles it spawns from atomic collisions travel in a variety of forward-ish directions, and it would seem at a variety of speeds as well. While at one level I could consider this some sort of propagating wave front, it's not that, and so when this cone of particles hits the detect

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[Areyoukiddingme]

However, there is a way to back track them using another particle often produced in association with high energy protons: neutrinos. These particles are neutral so they ignore magnetic fields and travel in straight lines but they are a lot, lot harder to detect. The experiment I work on, the IceCube Neutrino Observatory, is trying to do extactly this and we have had some success: we saw extremely high energy neutrinos that seemed to come from a blazar, a supermassive Black Hole at the centre of a galaxy that is emitting jets of high energy particles. We are looking for more sources but because it is hard to get neutrinos to interact we may need larger detectors.

It's worth noting here for the readers that there are several common fusion reactions which produce neutrinos. The biggest neutrino producer in our neighborhood is Sol. Detecting neutrinos is hard enough. Detecting distant neutrinos is much harder because Sol is a powerful noise source, and it even produces relatively high energy neutrinos itself when beryllium-7 in it snags an extra proton, turning it into (very unstable) boron-8 temporarily, which then burps out a positron (antimatter which promptly an

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[DesertNomad]

Thanks for that. And I thought I'd read that neutrinos apparently change flavors as they travel? Which can only further complicate matter (bad pun)

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[Roger W Moore]

Detecting distant neutrinos is much harder because Sol is a powerful noise source

No, it is not. As you point out, the energy of neutrinos from the sun is at the MeV level. The energy of these astrophysical neutrinos is around the PeV level: that's 9 orders of magnitude difference in energy. They are _really_ easy to separate. In fact, the detector I work on can't really even see MeV neutrinos from the sun even if we tried.

Detecting distance neutrinos is harder because there are far fewer of them because the source is so much further away.