Galactic center's gamma rays unlikely to originate from dark matter, evidence shows

February 3, 2016
Studies by two independent groups from the US and the Netherlands indicate that the observed excess of gamma rays from the inner galaxy likely comes from a new source rather than from dark matter. The best candidates are rapidly rotating neutron stars, which will be prime targets for future searches. The Princeton/MIT group and the Netherlands-based group used two different techniques, non-Poissonian noise and wavelet transformation, respectively, to independently determine that the gamma ray signals were not due to dark matter annihilation. Credit: Christoph Weniger

Bursts of gamma rays from the center of our galaxy are not likely to be signals of dark matter but rather other astrophysical phenomena such as fast-rotating stars called millisecond pulsars, according to two new studies, one from a team based at Princeton University and the Massachusetts Institute of Technology and another based in the Netherlands.

Previous studies suggested that coming from the dense region of space in the inner Milky Way galaxy could be caused when invisible dark collide. But using new statistical analysis methods, the two research teams independently found that the gamma ray signals are uncharacteristic of those expected from dark matter. Both teams reported the finding in the journal Physical Review Letters this week.

"Our analysis suggests that what we are seeing is evidence for a new astrophysical source of gamma rays at the center of the galaxy," said Mariangela Lisanti, an assistant professor of physics at Princeton. "This is a very complicated region of the sky and there are other astrophysical signals that could be confused with dark matter signals."

The center of the Milky Way galaxy is thought to contain dark matter because it is home to a dense concentration of mass, including dense clusters of stars and a black hole. A conclusive finding of dark matter collisions in the galactic center would be a major step forward in confirming our understanding of our universe. "Finding direct evidence for these collisions would be interesting because it would help us understand the relationship between dark matter and ordinary matter," said Benjamin Safdi, a postdoctoral researcher at MIT who earned his Ph.D. in 2014 at Princeton.

To tell whether the signals were from dark matter versus other sources, the Princeton/MIT research team turned to image-processing techniques. They looked at what the gamma rays should look like if they indeed come from the collision of hypothesized dark matter particles known as weakly interacting massive particles, or WIMPs. For the analysis, Lisanti, Safdi and Samuel Lee, a former postdoctoral research fellow at Princeton who is now at the Broad Institute, along with colleagues Wei Xue and Tracy Slatyer at MIT, studied images of gamma rays captured by NASA's Fermi Gamma-ray Space Telescope, which has been mapping the rays since 2008.

Dark matter particles are thought to make up about 85 percent of the mass in the universe but have never been directly detected. The collision of two WIMPs, according to a widely accepted model of dark matter, causes them to annihilate each other to produce gamma rays, which are the highest-energy form of light in the universe.

According to this model, the high-energy particles of light, or photons, should be smoothly distributed among the pixels in the images captured by the Fermi telescope. In contrast, other sources, such as rotating stars known as pulsars, release bursts of light that show up as isolated, bright pixels.

The researchers applied their statistical analysis method to images collected by the Fermi telescope and found that the distribution of photons was clumpy rather than smooth, indicating that the gamma rays were unlikely to be caused by collisions.

Exactly what these new sources are is unknown, Lisanti said, but one possibility is that they are very old, rapidly rotating stars known as . She said it would be possible to explore the source of the gamma rays using other types of sky surveys involving telescopes that detect radio frequencies.

Douglas Finkbeiner, a professor of astronomy and physics at Harvard University who was not directly involved in the current study, said that although the finding complicates the search for dark matter, it leads to other areas of discovery. "Our job as astrophysicists is to characterize what we see in the universe, not get some predetermined, wished-for outcome. Of course it would be great to find dark matter, but just figuring out what is going on and making new discoveries is very exciting."

According to Christoph Weniger from the University of Amsterdam and lead author of the Netherlands-based study, the finding is a win-win situation: "Either we find hundreds or thousands of millisecond pulsars in the upcoming decade, shedding light on the history of the Milky Way, or we find nothing. In the latter case, a explanation for the gamma ray excess will become much more obvious."

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NoStrings
2.1 / 5 (7) Feb 03, 2016
It was clear before this article: because there isn't any heavy dark matter, there can't be gamma rays produced by their non-existent collisions.
Neutrinos? Sure, I can admit them as the likeliest candidate, but no gamma rays there.
Tuxford
1.8 / 5 (10) Feb 03, 2016
"Either we find hundreds or thousands of millisecond pulsars in the upcoming decade, shedding light on the history of the Milky Way, or we find nothing. In the latter case, a dark matter explanation for the gamma ray excess will become much more obvious."


But no self-respecting merger maniac dare suggest that the source might be the core star itself (the grey hole). To do so would eliminate any potential future publication. Much safer to restate the dark matter fairy tale. Don't want to risk intellectual execution by the math fairies.
Whydening Gyre
2.7 / 5 (7) Feb 03, 2016
DM doesn't interact with Regular Matter.
Hence - a non-article.
flag
1 / 5 (4) Feb 03, 2016
RealityCheck
3 / 5 (2) Feb 03, 2016
Hi Whyde. :)
DM doesn't interact with Regular Matter.
Hence - a non-article.
In the overall context, the DM 'collisions' they hypothesize is between the hypothesized DM particles themselves, not between them and normal matter. Anyway, I tried to explain all these other possibilities/sources to many who believed that certain observed X-Rays and Gamma-Rays were 'supporting evidence' for both 'exotic' DM's existence and 'exotic' DM-DM 'mutual annihilation' collisions. Anyhow, I trust we are all 'on the same reality page' now that this group has finally dispelled much of the DM believers' supposed 'exotic entities, sources and behaviors' with down to earth 'non-exotic' and known real entities, sources and behaviors. Cheers . :)
Old_C_Code
2 / 5 (10) Feb 03, 2016
astrophysical phenomena such as fast-rotating stars called millisecond pulsars


Impossibly fast rotating stars, a star rotating in a fraction of a second is physically impossible unless you're inventing it on paper.
Hyperfuzzy
1.8 / 5 (5) Feb 03, 2016
Use the force Luke! See the reflection of all space and time with these 5 D spectacles. Only $5.99.
Whydening Gyre
4.2 / 5 (5) Feb 03, 2016
So... DM doesn't interact with regular matter. It doesn't even interact with itself.
Curiouser and curiouser...
And Hyper - I got mine at a "going out o business" sale for 2.99....
Whydening Gyre
4.2 / 5 (6) Feb 03, 2016
astrophysical phenomena such as fast-rotating stars called millisecond pulsars


Impossibly fast rotating stars, a star rotating in a fraction of a second is physically impossible unless you're inventing it on paper.

If they're dense enough, maybe not...
RealityCheck
4.3 / 5 (6) Feb 03, 2016
Hi Whyde, everyone. :)

About millisecond Pulsars and their 'rotation'. Be careful to note that it is the PRECESSING of the Neutron Star's POLES that is the milisecond rate, not the Neutron star's whole-body rotation. :)

The millisecond 'pulses' we observe (hence the name 'pulsars') results from the continuous polar jet 'beams' precessing and so producing a CONICAL SCANNING pattern of beam paths which scan across our position every millisecond. So it's NOT a millisecond rotation rate for the whole neutron star, it's the millisecond LIMITED PRECESSION CONE polar jet beam paths scanning rate, whose 'wobble' describes a very small 'circle' AT the polar region only, so it's not beyond physical possibility for the polar beam 'wobble' to produce such a millisecond 'hit rate' when it crosses our observing position HERE, and WITHOUT needing the whole Neutron star THERE to rotate at that rate. Ok? Cheers. :)
RealityCheck
5 / 5 (4) Feb 03, 2016
PS: It could be Nutating rather than Precessing I meant. But you get the point I trust. :)
torbjorn_b_g_larsson
4.4 / 5 (7) Feb 04, 2016
Since the trolls tries to paint those who accept consensus science as something else, I'll just point out that they can't explain the Planck legacy archive data nor why encyclopedias describe the reality like this:

"... the existence of dark matter is generally accepted ..."

[ https://en.wikipe...k_matter ]

Now can the frauds move to the anti-science sites they usually frequent? We have better things to do.

@WG: "So... DM doesn't interact with regular matter. It doesn't even interact with itself."

It does, or it wouldn't be particles (have to collide). The method has the constraint of WIMP DM, i.e. they would interact trough electroweak interactions. Then their mass would correspond to X-rays during annihilation, if they correspond to supersymmetric particles of standard particle model extensions. Those naturally get DM cross section - as constrained by their abundance - correct ("WIMP miracle").

[tbctd]
torbjorn_b_g_larsson
4.3 / 5 (6) Feb 04, 2016
Phys1
5 / 5 (4) Feb 04, 2016
DM doesn't interact with Regular Matter.
Hence - a non-article.

It is true that in order to be able to produce gamma rays, even by annihilation, the DM would have to be coupled to the EM field. The observation that no gamma's originate from DM extends the absence of optical emission to high energy.
Phys1
5 / 5 (3) Feb 04, 2016
cnt
So the paper is of fundamental importance.
Whydening Gyre
5 / 5 (1) Feb 04, 2016
@WG: "So... DM doesn't interact with regular matter. It doesn't even interact with itself."

It does, or it wouldn't be particles (have to collide). The method has the constraint of WIMP DM, i.e. they would interact trough electroweak interactions. Then their mass would correspond to X-rays during annihilation, if they correspond to supersymmetric particles of standard particle model extensions. Those naturally get DM cross section - as constrained by their abundance - correct ("WIMP miracle").

@TBGL
Was a simple musing of this study's apparent null result that compounds the DM question. My "artist" mind is always seeking simpler, forehead-smacking answers to complex situations. It's the curse of "gyre"...:-)

Whydening Gyre
5 / 5 (3) Feb 04, 2016
I do think the statement of -
"... the existence of dark matter is generally accepted ..."

should not be expressed without the proviso of -
"- alternative theories, such as MOND and TeVeS try to account for the observations without invoking additional matter. "

which, in turn, should not be expressed without the proviso of -
"However, these theories cannot account for the properties of galaxy clusters."


Just sayin'...
vidyunmaya
1 / 5 (1) Feb 04, 2016
Sub: Himalayan Wisdom- in search of Origins
Plasma Regulated electro-magnetic phenomena in magnetic field Environment-holds the key at milky-way Galactic plane
Now search from the heart and Center of the universe-say 100,000 LY from the Milkyway. control and Regulation -part of Space Cosmology vedas interlinks. Books available at LULU. welcome East West Interaction.http://www.lulu.c...039.html
Whydening Gyre
not rated yet Feb 04, 2016
DM doesn't interact with Regular Matter.
Hence - a non-article.

It is true that in order to be able to produce gamma rays, even by annihilation, the DM would have to be coupled to the EM field. The observation that no gamma's originate from DM extends the absence of optical emission to high energy.

Are you saying that the higher the energy level, the lesser the light emission?
That DM maintains a higher frequency and/or charge?
Phys1
3 / 5 (2) Feb 05, 2016
DM doesn't interact with Regular Matter.
Hence - a non-article.

It is true that in order to be able to produce gamma rays, even by annihilation, the DM would have to be coupled to the EM field. The observation that no gamma's originate from DM extends the absence of optical emission to high energy.

Are you saying that the higher the energy level, the lesser the light emission?
That DM maintains a higher frequency and/or charge?

I am saying that this shows that also at high energies there is no optical emission at all that would correspond to DM. Already it was clear that at many lower frequencies there is no trace of light emission or absorption by DM. So no proof of DM here.
Reg Mundy
3.3 / 5 (4) Feb 07, 2016
Betcha it's "millisecond pulsars", so another nail in the DM coffin.
The only "real" evidence for DM is that it must exist if Newton/Einstein view of gravity is correct.
I think they got it wrong, gravity does not exist as a force, and the "effects" can be explained otherwise without the need for DM, DE, GW, WIMPS, etc. It all goes back to Newton dreaming up this imaginary force when he was high on hemp, or getting bumped on the head by a very large apple....
TopCat22
3 / 5 (1) Feb 07, 2016
There is no evidence that Dark Mater is a thing in its own right. My view is that it is a property (a change in constants if you will) of space-time that becomes evident at very large mass scales and not measurable at smaller scales. I also believe it is related to black holes in such a way that the energy that goes into the black holes in an area causes it. Perhaps a viscosity type change in the space-time matrix that gives the locality a different constant for the gravitational-time.
Phys1
5 / 5 (1) Feb 07, 2016
@TC22
Is your view in agreement with observation? Are there any observations, performed or imaginable, that distinguish your view and the DM hypothesis ?
If not, what are you talking about ?
viko_mx
1 / 5 (1) Feb 08, 2016
Еlementary particles move in the structure of vacuum of space and their interactions with this structure determine their behavior. This structure is programmable and propagates electromagnetic waves. It is not difficult to understand that the electromagnetic waves can not spread into nothingness or abstract geometric space, but only in a real physical environment with the natural characteristics and constraints.
TopCat22
not rated yet Feb 09, 2016
@TC22
Is your view in agreement with observation? Are there any observations, performed or imaginable, that distinguish your view and the DM hypothesis ?
If not, what are you talking about ?


I am not a scientist or a researcher. I am an amateur of the subject at hand. Form everything I've read on the subject my intuition tells me these is a relationship between what happens with blackholes and where all that energy ends up after falling in. The energy that fell in was in my humble opinion transformed into an effect on the space-time that we can mistake for the effects of dark-mater... simpler to consider it an effect of space-time than start making up make believe particles that cannot be felt or found... might as well say god willed it so rather than make up dark mater to account for an effect on space-time that can be many other things... my idea is but one and its as good as dark-mater since there is not a shred of evidence for a dark mater either.

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