Gamma rays from galactic center could be evidence of dark matter

Aug 13, 2012

( -- Gamma-ray photons seen emanating from the center of the Milky Way galaxy are consistent with the intriguing possibility that dark-matter particles are annihilating each other in space, according to research submitted by UC Irvine astrophysicists to the American Physical Society journal Physical Review D.

Kevork Abazajian, assistant professor, and Manoj Kaplinghat, associate professor, of the Department of Physics & Astronomy analyzed data collected between August 2008 and June 2012 from NASA's Fermi Gamma-ray Space Telescope orbiting Earth. They found more gamma-ray photons coming from the Milky Way than they had expected, based on previous scientific models. Gamma-rays are electromagnetic radiation emitted during radioactive decay or other high-energy particle processes.

"This is the first time this new source has been observed with such high statistical significance, and the most striking part is how the shape, spectrum and rate of the observed gamma rays are very consistent with the leading theories for dark matter," Abazajian said. "Future observations of regions with less astrophysical emission, such as dwarf galaxies, will be able to conclusively determine if this is actually from the dark matter."

Nonluminous and not directly detectable, dark matter is thought to account for 85 percent of the universe's mass. Its existence can only be inferred from its gravitational effects on other, visible matter. The UCI researchers' findings could support its presumed presence at the center of galaxies.

The prevailing hypothesis is that dark matter is composed of weakly interacting massive particles, or WIMPs. When two WIMPs meet, they annihilate each other to produce more familiar particles – including gamma rays.

Although the data interpretation seems to be consistent with theory, the could be coming from a source other than WIMP destruction, Kaplinghat noted. "The signal we see is also consistent with photons emitted by pulsars," he said, "or from high-energy particles interacting with gas in the galactic center."

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User comments : 18

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2.7 / 5 (12) Aug 13, 2012
No, that is a stupid and baseless idea. Who writes this stuff?
2.7 / 5 (14) Aug 13, 2012
They're simply stating that photons from a source they can't identify, might be coming from a hypothetical source they can't identify! (duh)
3.7 / 5 (9) Aug 13, 2012
It seems like people are just fumbling around in the dark on this matter. (intended)
It makes me (as a tradesman) think, do these people really know what they're talking about ?
2.5 / 5 (13) Aug 13, 2012
more gamma-ray photons coming from the Milky Way galactic center than they had expected


That, or a giant exploding sasquatch.
2.1 / 5 (7) Aug 13, 2012
All they are saying here is that they have significant evidence indicating that dark matter theory is still quite promising. They are not claiming a discovery of dark matter. This is how science works. We collect enough data to see how well the theory fits in order to make progress. They are certainly not stupid people making up stuffs. If only the readers understand how the process of science operates before they make senseless comments about the article. Or maybe they need to be educated more about the nature of physics. Gamma ray telescope from NASA has come a long way and is making flawless progress about the nature of the universe. Much more data is needed for confirmation of the theory. Awesome work.
2.8 / 5 (9) Aug 13, 2012
It seems like people are just fumbling around in the dark on this matter. (intended)
It makes me (as a tradesman) think, do these people really know what they're talking about ?
They certainly do for your information
1.8 / 5 (5) Aug 13, 2012
Well if one of my gamma rays burst i'd call a tradesman. I can't even bleed my own radiators!
2 / 5 (12) Aug 13, 2012
"dark matter is thought to account for 85 percent of the universe's mass."

Which nonexpanding universe is that?
3 / 5 (6) Aug 13, 2012
I sure wish some of my colleagues from SLAC can jump in to put some sense to the comments. GRB is a very strong signal for dark matter even though it is not a direct confirmation as there are other explanations for it as well. Nobody can ignore and overlook the gravitational effects which points to dark matter theory. It is statistically significant but again not a discovery claim. MOND cannot account for cluster of galaxies as well as dark matter theory.
2.7 / 5 (7) Aug 14, 2012
From the nature of the comments on here you'd think dark matter went around stealing all your girlfriends in high school.
3 / 5 (2) Aug 14, 2012
If dark matter are annihilating each other then their gravitational effects are changing over time. This should be incorporated into models on the behavior of dark matter as the universe evolved in time.

This should give some constraints on what dark matter is and how it behaves. If the gamma ray background is too high then the concentration of dark matter in the past would have been much higher and that should have had a noticeable effect on the evoluation of the cosmos.

I have yet to see any studies on dark matter that accounted for self annihilation. It would be interesting and might help to say if dark matter is real and if the gamma ray background comes from.
4.3 / 5 (6) Aug 14, 2012
As usual, physorg presumes their audience All have subscriptions to PhysRev. NOT TRUE. A simple referral to the arxiv allows readers to access tech. details For Free:
This story is much ado about nothing. Not only have 30 Gev DM candidates been rigorously excluded by XENON100, but this wolf-cry went out about 3 yrs ago, when PAMELA found a similar signature. It has since crashed, as this one will too.
1.7 / 5 (6) Aug 14, 2012
Dark matter has a tendency to accumulate AROUND galaxies, not at their centres. IMO gamma rays observed are generated with reaction of fast neutrinos generated with galactic center with CMBR background and interstellar gas nearby.
2 / 5 (4) Aug 14, 2012
It makes me (as a tradesman) think, do these people really know what they're talking about?
If it is "dark matter" they are talking about, then they quite certainly DO NOT (yet) ;-)

And as allready pointed out at the very end of the article, the signals are consistent with a myriad of other KNOWN possible candidates. Ergo the sources are not pinned down yet, so might as well just attribute it to anything that could possibly "fit the bill", and publish a paper about it..

That's all it takes :-)
1 / 5 (2) Aug 14, 2012
On a side note, is dark matter expected to interact with the Higgs field to give it mass or is it expected to get it's mass like the quarks do from a different mechanism?
Infinite Fractal Consciousness
1 / 5 (3) Aug 16, 2012
Science-haters gonna hate.

Every article on PhysOrg:
"Scientists observed something."

Most responses:
"See, science doesn't know everything! It's a scam!"

1.6 / 5 (7) Aug 17, 2012
...could be evidence of dark matter

...or not.

Gamma-ray photons seen emanating from the center of the Milky Way galaxy are consistent with the intriguing possibility that dark-matter particles are annihilating each other in space...

"...are consistent with"? Really? For a backwards-built hypothesis sans reasonable guesswork along the lines of "how", this sound an awful lot like it is an example of the formal logical fallacy called "affirming the consequent".

It is only "consistent" with a purely hypothetical scenario where imaginary elements interact to produce that specific result. This is supposed to be science, not magic, but replace "dark matter" with "tap-dancing unicorns" and you achieve the exact same level of logical validity.

They found more gamma-ray photons [snip] than they had expected, based on previous scientific models.

So... they falsified the previous scientific models but decided to try to patch, rather than abandon, them. Excelsior!
1 / 5 (2) Aug 24, 2012
Let me try and be a bit clearer.

Dark matter does not make make up 85 percent of the mass of the universe.

It may make up 85 percent of the matter but not the mass.

In this link you say it is 83 percent of the matter.

Please get your figures right and your concept of mass, matter and energy density right.

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