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Tunga
2004-Sep-14, 02:20 AM
I was contemplating one of the mysteries of the universe today and I wondered if anyone on Bad Astronomy might have thoughts on the subject.

Galactic cosmic rays (GCRs) are high-energy charged particles that originate outside our solar system. About 85% are protons (nuclei of hydrogen atoms), 12% alpha particles (helium nuclei) and the remainder are electrons and the nuclei of heavier atoms. The origin of GCRs are thought to be from supernova explosions.

The mystery is why are there so few electrons! Intuitively, it would seem that just as many electrons as protons are release during a supernova event. So where did all the electrons go?

A quick search of WWW indicated that the galactic magnetic field is highly concentrated along the plane of the galaxy. Also the galactic magnetic field lines up with the galactic spiral arms.

I stumbled across a presentation “The Propagation of Ultra High Energy Cosmic Rays in the Galactic Magnetic Fields” by A. Elyiv and B. Hnatyk. Pages 6 & 7 of this presentation gave an interesting pictorial of the magnetic fields and the influence on very high-energy cosmic rays. Refer to:

http://64.233.179.104/search?q=cache:8ZNC9DjgLcgJ:phacts.phys.lsu.edu/ISCRA/ISCRA_Docs/elyiv.ppt+Cosmic+Rays+elyiv+hnatyk&hl=en

This leads me to wonder if the spiral fields act as giant magnetic conduits where protons are generally contained in one color conduit and electrons are generally constrained in the other color conduit. As our solar system travels around the galaxy, it crosses from blue to red to blue conduits. So in time we might cross the line and experience a preponderance of GCRs primarily composed of electrons. At the outer reached of the galaxy, the magnetic conduits strength weakens, the protons and electrons merge together and interact producing new hydrogen clouds, that are pulled back into the galaxy to begin the process anew with star formation.

scourge
2004-Sep-14, 06:02 AM
Perhaps the numbers you've indicated are ratios -by mass-, not number, in which case, there may well be equal numbers of protons and electrons in circulation...this came up in the solar electron energy thread recently. Given the mass ratios, equal quantities of electrons would be less than 1% of the composition of cosmic particles, just like with solar wind.

What I'd like to know, is the average energy content of these galactic and solar electrons--I'd think they'd have a similar average kinetic energy to the protons...but that's a guess.

If your conduit idea is right, I'd think there must be a way to gauge their position and density somehow--an interesting line of inquiry Tunga...maybe we could learn something about field containment of extremely high energy particles from the galaxy...

Tunga
2004-Sep-14, 03:32 PM
Scourge
Thanks for your comments. It looks like the count is by particles rather than mass ratios. As an example, refer to:
http://www-d0.fnal.gov/~diehl/Public/snap/meetings/SNAP05-20-2004.ppt
Am I reading this wrong?

"The Galactic Electrons have ~100x lower flux than the protons."

Tunga
2004-Sep-14, 05:09 PM
O.K. I think I understand it now. Detectors have a minimum threshold. So if you have electrons and protons traveling at the same speed, the electrons because their mass is around 100 times smaller than protons will have energy levels around 100 times lower than the protons. Therefore the detector's cut-off comes into play. The electrons are still there, they are just not being picked up by the detectors because they fail to trip the energy levels to register.