Axions, the Sun and dark matter

[Laurie61]

Curious Signal Could Be Dark Matter Pouring From The Sun's Core.

This could be historic: Astronomers from Leicester University have detected a strange signal in the X-ray spectrum that appears to be a signature of 'axions' — a hypothetical dark matter particle. It could take years to confirm, but this may be the first direct detection and identification of dark matter.

The potential discovery of axions was found through an exhaustive study of practically the entire archive collected by the ESA's X-ray observatory, XMM-Newton. That's 14 years of X-ray observations! In particular, the scientists were looking at data where there appeared to be an unexpected seasonal modulation in the X-ray flux — modulations consistent with the conversion of axions churned-out by the Sun into X-ray photons as they pass through the Earth's magnetic field. To date, other hunts for the elusive elementary particle have come up nil, including those conducted at CERN and by other spacecraft.

Normally, the X-ray background — the sky after galaxies, stars, and other bright X-ray sources have been filtered out — appears to be unchanged when it's observed.

"However, we have discovered a seasonal signal in this X-ray background, which has no conventional explanation, but is consistent with the discovery of axions," noted study co-author Andy Read in a statement. Given the dearth of explanations, the researchers turned to more radical theories, including the suggestion that axions — the theoretical particles of dark matter — are streaming from the core of the Sun and producing X-rays when they smash into the Earth's magnetic field.

According to the researchers, it's possible that axions are produced in the core of the Sun and that they convert to X-rays in the magnetic field of the Earth. It has been suggested that the X-ray signal due to axions will be at its greatest when observered through the sunward side of the magnetic field — the place where the field is strongest. The researchers noticed that the intensity of X-rays rose by about 10% whenever the spacecraft measured the boundary of Earth's magnetic field that faces towards the Sun.

If these particles are indeed axions, then they must be incredibly light, featuring a mass of around a hundred billionth of an electron.

http://io9.com/curious-signal-could-be-dark-matter-pouring-from-the-su-1647581644

http://www.bbc.co.uk/news/science-environment-29662282

[bomberbaz]

I love the science behind astronomy, never ceases to amaze me the stuf the come up with. Really hope something comes of this.

[Knight of Clear Skies]

Thanks for posting, will be interesting to see what comes out of this. Can't say I understand the implications of dark matter does turn out to be largely composed of axions, but I'll keep my eye open for any articles that explain this.

[ronin]

According to the researchers, it's possible that axions are produced in the core of the Sun and that they convert to X-rays in the magnetic field of the Earth.

Why then would they not turn into X-rays in the magnetic field of the Sun?

That sort of implies that the magnetic field of the Earth is fundimentally different to that of the Sun.

[bomberbaz]

Why then would they not turn into X-rays in the magnetic field of the Sun?

That sort of implies that the magnetic field of the Earth is fundimentally different to that of the Sun.

Thats a good point ronin, maybe because they (axiions) are firing out of the sun its magnetic field behaves differently with them than when they hit our own MF!

[Laurie61]

There's a bit more on this here, it does sound as though they are being quite cautious and not claiming this is definitely evidence ->

" But although the paper has been accepted by Monthly Notices of the Royal Astronomical Society and is to be published on October 20, the surviving authors are not popping champagne corks just yet. “We found an unusual result that we can't explain by any conventional method, and this axion theory does explain it,” says co-author Andy Read, an astronomer at Leicester. “But it is just a hypothesis, and most hypotheses don't make it,” he adds."

In their 67-page paper, the researchers did their best to rule out more mundane phenomena — such as interaction between the solar wind and Earth’s magnetic field — as the cause of the excess, Read says, before invoking axions as a source.

The authors also show that hints of a similar signal can be found in data produced by NASA’s Chandra X-Ray Observatory, although a formal corroboration will take more data and years of analysis.

http://www.scientificamerican.com/article/physicists-see-potential-dark-matter-from-the-sun/

[Ptarmigan]

Why then would they not turn into X-rays in the magnetic field of the Sun?

That sort of implies that the magnetic field of the Earth is fundimentally different to that of the Sun.

Or that the axions generated in the sun are not of the right QCD flavor there to interact in that way.

Perhaps they need travel time/distance to oscillate between flavors.

(like neutrinos and the solar neutrino deficit problem)

I did a google on " axion oscillate flavor " but soon got befuseled and way outside my pay grade !!

[Ptarmigan]

Ah ha ! Found it,

"axion-photon oscillation phenomenon"
my head hertz, I wish I had paid more attention to Lagrangians 40y ago
(my emboldings)

http://pdg.lbl.gov/2009/reviews/rpp2009-rev-axions.pdf
Axions (Rev.) - Particle Data Group

Axions have a characteristic two-photon vertex, inherited
from their mixing with π0 and η. It allows for the main search
strategy based on axion-photon conversion in external magnetic
fields [5], an effect that also can be of astrophysical interest.

etc and >>
(page 5)

II.1 Photon regeneration
Searching for “invisible axions” is extremely challenging.
The most promising approaches rely on the axion-two-photon
vertex, allowing for axion-photon conversion in external electric
or magnetic fields [5]. For the Coulomb field of a charged
particle, the conversion is best viewed as a scattering process,
γ + Ze ↔ Ze + A, called Primakoff effect [22]. In the other
extreme of a macroscopic field, usually a large-scale B-field, the
momentum transfer is small, the interaction coherent over a
large distance, and the conversion is best viewed as an axion-
photon oscillation phenomenon in analogy to neutrino flavor
oscillations [23].

[Knight of Clear Skies]

Interesting, but more than a little beyond me. I'll have to wait for the scientific blogging community to catch up on this one.

[Ptarmigan]

Yer, me too

there is another 20odd pages of that to go !

and they are invoking two, yes TWO!, Higgs fields,

I think I stuffed my laptop, it crashed and I had to power down my internet dongle to get it to be recognised again, (the gods doth protest methinks )

I think I am back and I promise not to do any more digging, , , for now

:)

[symesie04]

Hmm interesting although i dont dare to pretend i totally understand the implications. But just a thought on the Axxions interaction with the Suns magnetic field, could it be that like photons that the Axxions are initially trapped bu the field but as the field snaps and releases tension the Axxions as well as photons are released without to much further interaction? After all the complete actions of the Suns magnetic field are not entirely understood and maybe the snapping of the fields that leads to millions of tonnes of plasma being ejected into space also produces clear paths of non interaction that the axxions pass threw.

Not sure i understood the article right but is it suggesting that the basis of dark matter is created within stars? If so that would have a fundamental impact on our current very shaky idea of how galaxies work and form. At present i think its thought that dark matter helps herd matter together, bond galaxies and keep them in in clustered order. But if dark matter is produced in stars then surely its a chicken and egg thing? Surely stars gathered in galaxies had to produce the dark stuff before it could bind galaxies together etc?

[bomberbaz]

Not sure i understood the article right but is it suggesting that the basis of dark matter is created within stars? If so that would have a fundamental impact on our current very shaky idea of how galaxies work and form. At present i think its thought that dark matter helps herd matter together, bond galaxies and keep them in in clustered order. But if dark matter is produced in stars then surely its a chicken and egg thing? Surely stars gathered in galaxies had to produce the dark stuff before it could bind galaxies together etc?

Not necessarily symesie, in the beginning stars were huge blue giants and these burnt fiercely but for short periods of time before becoming supernovas. So I suppose theoretically these huge stars and the immense gravity from them and the dark matter they were creating at a massive rate could have brought together small clusters ( a few hundred million) of these blue giants that over time became lots of smaller types of suns as they SN'd and spread their matter around and spread into larger galaxies of billions of stars. 

Of course this is only a guess as i have never seen it written this way but who really knows?

Steve

[symesie04]

Maybe but i thought even as early as the first giants ignited that they had already began to be loosely grouped into the 13+ billion year old chaotic galaxies we see with Hubble today?  Thats the point isnt current thought that dark matter was formed at or almost at the point of the big bang? which then has kind of condensed into strings (maybe due to expansion) throughout the universe. Everything there after has formed in or around these fillaments of dark matter, hence the map of the universe recently created which shows all galaxies arranged into huge structures around what appears to be fillaments of dark matter. But of course if dark matter is created within stars????

[bomberbaz]

maybe its still being created today hence the reason for continuos expansion but that significant amounts were also created during the rapid expansion period and in the flux soup of the early universe