Mystery source of cosmic ray bombardment

[Royston]

I've been on the RSS feed for Universe Today for some time now, but this article in particular caught my eye. Partly because it affects Earth directly, but I found the possible cause of these cosmic rays due to dark matter annihilation more interesting...

 

http://www.universetoday.com/2008/11/19/cosmic-rays-from-mysterious-source-bombarding-earth/

 

From the article...

 

The new results show an unexpected surplus of cosmic ray electrons at very high energy — 300-800 billion electron volts — that must come from a previously unidentified source or from the annihilation of very exotic theoretical particles used to explain dark matter.

"This electron excess cannot be explained by the standard model of cosmic ray origin," said Wefel. "There must be another source relatively near us that is producing these additional particles."

According to the research, this source would need to be within about 3,000 light years of the sun. It could be an exotic object such as a pulsar, mini-quasar, supernova remnant or an intermediate mass black hole.

The scientists point out, however, that there are few such objects close to our solar system.

The nature of dark matter is not understood, but several theories that describe how gravity works at very small, quantum distances predict exotic particles that could be good dark matter candidates.

"The annihilation of these exotic particles with each other would produce normal particles such as electrons, positrons, protons and antiprotons that can be observed by scientists," said Eun-Suk Seo, ATIC lead at the University of Maryland, College Park.

 

I realize it's a 'wait and see', to eliminate the latter if such an object is found near our solar system, however although not being an expert on dark matter and how it interacts, I was surprised that this was considered.

Are they jumping the gun with putting this explanation forward, or are the models that describe dark matter annihilation (or at least these particular dark matter candidates) sound enough for this to be a serious candidate for these cosmic rays ?

In any case, it's certainly a discovery that's worth following.

[Arch2008]

http://news.yahoo.com/s/space/20081106/sc_space/mysteriousdarkmattermightactuallyglow

“A new computer simulation of the evolution of a galaxy like our Milky Way suggests it might be possible to observe high-energy gamma-rays given off by dark matter.”

 

This seems to be what the computer models had predicted. Marcus and I discussed this at

 

http://www.scienceforums.net/forum/showthread.php?t=36258

 

Curious, that White’s prediction wasn’t mentioned by Atkinson in her report. It would be interesting to see if the source is toward the center of the galaxy, as White also predicts.

[Martin]

Good find, Snail. Here's some more on it:

http://www.newsdesk.umd.edu/scitech/release.cfm?ArticleID=1793

 

Here's the first paragraph of the article publshed in Nature, the 20 November edition

 

http://www.nature.com/nature/journal/v456/n7220/abs/nature07477.html

 

The full article is pay-per-view, but the first paragraph is a free sample. We will get more on this I expect. Publication in Nature is a sign that it is solid and quite possibly important.

 

Since the paragraph is short, I'll just quote it to save folks having to go there:

 

An excess of cosmic ray electrons at energies of 300–800 GeV

 

 

 

"Galactic cosmic rays consist of protons, electrons and ions, most of which are believed to be accelerated to relativistic speeds in supernova remnants1, 2, 3. All components of the cosmic rays show an intensity that decreases as a power law with increasing energy (for example as E -2.7). Electrons in particular lose energy rapidly through synchrotron and inverse Compton processes, resulting in a relatively short lifetime (about 10^5 years) and a rapidly falling intensity, which raises the possibility of seeing the contribution from individual nearby sources (less than one kiloparsec away)4. Here we report an excess of galactic cosmic-ray electrons at energies of approx300–800 GeV, which indicates a nearby source of energetic electrons. Such a source could be an unseen astrophysical object (such as a pulsar5 or micro-quasar6) that accelerates electrons to those energies, or the electrons could arise from the annihilation of dark matter particles (such as a Kaluza–Klein particle7 with a mass of about 620 GeV)."

[Royston]

EDIT: Oops, this was in response to Arch (below), Martin posted at the same time.

 

Thanks for the links, after posting I found this article (New Scientist) where I can see now that dark matter annihilation is being considered in this instance (as well as what you've provided, Arch)...for some reason I thought the ideas behind the source of positrons (from the centre of the Milky Way) et.c was very much divided, but clearly I was wrong...obviously the source from my OP, is more local.

 

The article gives some historical background, and future developments of discovering the nature of dark matter, so is worth a read as a summary if nothing else...

 

http://www.newscientist.com/article/mg19926702.600-has-dark-matters-telltale-signature-been-spotted.html

Edited November 21, 2008 by Snail

[Mr Skeptic]

Yes, I've seen this story too. If it truly is dark matter, that would be very interesting. It would be nice to finally start nailing down some specifics on dark matter, such as mass.

[Arch2008]

It's like reading a great crime novel and seeing the threads of evidence come together.