No trace of dark matter in gamma-ray background

December 19, 2016, University of Amsterdam
The data that were analysed in the work described here. Fluctuations in the isotropic gamma-ray background, based on 81 months of data. Emission from our own Galaxy, the Milky Way, is masked in grey. Credit: Mattia Fornasa, UvA/Grappa

Researchers from the University of Amsterdam's (UvA) GRAPPA Center of Excellence have just published the most precise analysis of the fluctuations in the gamma-ray background to date. By making use of more than six years of data gathered by the Fermi Large Area Telescope, the researchers found two different source classes contributing to the gamma-ray background. No traces of a contribution of dark matter particles were found in the analysis. The collaborative study was performed by an international group of researchers and is published in the latest edition of the journal Physical Review D.

Gamma rays are particles of light, or photons, with the highest energy in the universe and are invisible to the human eye. The most common emitters of are blazars: supermassive black holes at the centers of galaxies. In smaller numbers, gammy rays are also produced by a certain kind of stars called pulsars and in huge stellar explosions such as supernovae.

In 2008 NASA launched the Fermi satellite to map the gamma-ray universe with extreme accuracy. The Large Area Telescope, mounted on the Fermi satellite, has been taking data ever since. It continuously scans the entire sky every three hours. The majority of the detected gamma rays is produced in our own Galaxy (the Milky Way), but the Fermi telescope also managed to detect more than 3000 extragalactic sources (according to the latest count performed in January 2016). However, these individual sources are not enough to explain the total amount of coming from outside our Galaxy. In fact, about 75% of them are unaccounted for.

Isotropic gamma-ray background

As far back as the late 1960s, orbiting observatories found a diffuse background of gamma rays streaming from all directions in the universe. If you had gamma-ray vision, and looked at the sky, there would be no place that would be dark.

The source of this so-called isotropic gamma-ray background has hitherto remained unknown. This radiation could be produced by unresolved blazars, or other sources too faint to be detected with the Fermi telescope. Parts of the gamma-ray background might also hold the fingerprint of the illustrious particle, a so-far undetected particle held responsible for the missing 80% of the matter in our universe. If two collide, they can annihilate and produce a signature of gamma-ray photons.

This view shows the entire sky in gammy ray radiation, at energies greater than 1 GeV, based on five years of data from the Large Area Telescope instrument on NASA's Fermi Gamma-ray Space Telescope. Brighter colours indicate brighter gamma-ray emission. The large bright band in the middle is the emission from our own Galaxy. Credit: NASA/DOE/Fermi LAT Collaboration

Fluctuations

Together with colleagues, Dr Mattia Fornasa, an astroparticle physicist at the UvA and lead author of the paper, performed an extensive analysis of the gamma-ray background by using 81 months of data gathered by the Fermi Large Area Telescope – much more data and with a larger energy range than in previous studies. By studying the fluctuations in the intensity of the gamma-ray background, the researchers were able to distinguish two different contributions to the gamma-ray background. One class of is needed to explain the fluctuations at low energies (below 1 GeV) and another type to generate the fluctuations at higher energy – the signatures of these two contributions is markedly different.

In their paper the researchers suggest that the gamma rays in the high-energy ranges – from a few GeV up – are likely originating from unresolved blazars. Further investigation into these potential sources is currently being carried out by Fornasa, fellow UvA researcher Shin'ichiro Ando and colleagues from the University of Torino, Italy. However, it seems much harder to pinpoint a source for the fluctuations with energies below 1 GeV. None of the known gamma-ray emitters have a behaviour that is consistent with the new data.

Constraints on dark matter

To date, the Fermi telescope has not detected any conclusive indication of gamma-ray emission originating from dark-matter particles. Also, this latest study showed no indication of a signal associated with dark matter. Using their data, Fornasa and colleagues were even able to rule out some models of dark matter that would have produced a detectable signal.

'Our measurement complements other search campaigns that used gamma rays to look for dark matter and it confirms that there is little room left for dark matter induced gamma-ray emission in the isotropic gamma-ray background,' says Fornasa.

Explore further: NASA's Fermi mission expands its search for dark matter

More information: 'The Angular Power Spectrum of the Diffuse Gamma-ray Emission as Measured by the Fermi Large Area Telescope and Constraints on its Dark Matter Interpretation' in Physical Review D. D 94, 123005, 9 December 2016. dx.doi.org/10.1103/PhysRevD.85.083007

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38 comments

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Benni
1.6 / 5 (13) Dec 19, 2016
Using their data, Fornasa and colleagues were even able to rule out some models of dark matter that would have produced a detectable signal.


I guess DM Enthusiasts will simply need to look elsewhere for the Inferred Gravity Narrative.

This of course will come as a great disappointment to the Zwicky acolytes who live in this chatroom. Their excuses for looking in mirrors everyday & pretending all that BMI is 80-95% Missing Matter becomes even more of a cascade of diminishing excuses as a result from living in the land of DM fantasy & all that non-existent Cosmic Fairy Dust.......next, on to Black Holes & Schneibo's pictures of them.
gkam
1.9 / 5 (14) Dec 19, 2016
I'm a-tellin' ya, Dark Matter is just gravity leaked from mass in another dimension. No kidding.
Bigbangcon
1 / 5 (7) Dec 19, 2016
The source of diffuse gamma-ray in the Milky Way Galaxy and elsewhere in the universe and also the sources of more narrow and point types, have been explained on the basis of matter-antimatter annihilation processes. But of course, in that case one has to forget about the Big Bang and accept a dialectical view of an eternal and infinite universe - a paradigm shift that modern official physics is unwilling to accept! https://philpaper...c/MALTCG
Benni
1.4 / 5 (10) Dec 19, 2016
I'm a-tellin' ya, Dark Matter is just gravity leaked from mass in another dimension. No kidding.


Yep, entertainment via the Tinfoil Hat crowd is already starting to make it's appearance. By the way geek, I sent your address over to the Nat Am tribe nearest you, no kidding.
cantdrive85
1.6 / 5 (7) Dec 19, 2016
Look at these crankpots trying to claim DM doesn't exist. A feeble attempt to claim 80 percent of the missing Universe is missing even more than we thought. We know where and what this DM is not to mention where the gamma ray sources are from.
Can be seen here;
https://www.googl...;bih=652
And the gamma ray sources here;
https://www.googl...;bih=652#tbm=isch&q=unicorn+light
gkam
2 / 5 (8) Dec 19, 2016
"By the way geek, I sent your address over to the Nat Am tribe nearest you, no kidding."
--------------------------

Hilarious.

Someone get to you? Hurt your feelings?
gkam
2 / 5 (8) Dec 19, 2016
I'm a-tellin' ya, Dark Matter is just gravity leaked from mass in another dimension. No kidding.

"Yep, entertainment via the Tinfoil Hat crowd is already starting to make it's appearance"

Prove me wrong.
Benni
1.9 / 5 (9) Dec 19, 2016
I'm a-tellin' ya, Dark Matter is just gravity leaked from mass in another dimension. No kidding.

"Yep, entertainment via the Tinfoil Hat crowd is already starting to make it's appearance"

Prove me wrong.
........you showed up.
gkam
2.1 / 5 (7) Dec 19, 2016
Here 'tis: According to string folk, we exist in a universe with maybe ten dimensions, but we exist in only four of them. The others, they say, are tiny around our dimensional boundaries. I contend those tiny places are just the contact points between dimensions, and once through one, you will find other aspects of the Universe.

Dark Matter is extradimensional mass.

Go differentiate that, benni.
cantdrive85
2.8 / 5 (9) Dec 19, 2016
The extra dimensions are where the unicorns and leprechauns reside, try and prove me wrong!
Uncle Ira
3.6 / 5 (17) Dec 19, 2016
Here 'tis:
This ought to be great big fun.

According to string folk, we exist in a universe with maybe ten dimensions, but we exist in only four of them.
You understand String Theory enough to explain to all us goobers why you think it might be right?

The others, they say, are tiny around our dimensional boundaries.
What it is that makes them say that?

I contend those tiny places are just the contact points between dimensions, and once through one, you will find other aspects of the Universe.
I contend you are doing your pretend to know something you don't know again.

Dark Matter is extradimensional mass.
Do you got the mechanism for that or is it something you read somewhere and thought it would be smart trying to repeat it here?

Go differentiate that, benni.
Instead of telling him to differentiate it, why you don't explain what type of maths are involved in String Theory? I bet you can't without ending up looking really silly.
gkam
2 / 5 (8) Dec 19, 2016
I was counting on you. It ain't my field. But you are the alleged "real" engineer, so take over.

No copying from others.

It is just my theory, and was presented as such. I welcome any proof of it being wrong.
Uncle Ira
3.8 / 5 (13) Dec 19, 2016
It is just my theory, and was presented as such.
It was not "your" theory. It was you trying to parrot something again and got called on it. I am sure a genius like you don't need the explanation of what the word theory means on a science interweb place

I welcome any proof of it being wrong.
Nice try Skippy. But it is "your" theory, it's on you to explain it. Answer questions about it. You have not thrown out anything that can be challenged. You might as well be saying that it is the invisible herds of unicorns.

How can anybody give the proofs when you don't even know what kind of maths are involved. Clue: Proofs are maths things, not theory things.
Uncle Ira
3.2 / 5 (11) Dec 19, 2016
P.S. for you glam-Skippy.

What I am trying to say Cher is that the stringy theories went out of vogue some time ago. They are not falsifiable, so they are not physical. At this point in time, all they are is some really fancy maths that a few peoples play around with. Metaphysics,,, look it up.
gkam
2.7 / 5 (9) Dec 19, 2016
No, your point is that you have a fixation on getting even with me for being real.
Uncle Ira
3.3 / 5 (12) Dec 19, 2016
No, your point is that you have a fixation on getting even with me for being real.


You always whine that you only want to discuss the science and the articles, then when somebody tries you whine that peoples are being mean to you. Cher you are truly a remarkable moron, even for a moron.
gkam
2.3 / 5 (9) Dec 19, 2016
Fixated.

You are absolutely fixated.

Get over it.
Benni
1.5 / 5 (8) Dec 19, 2016
OK geek & Ira, knock it off........we need better entertainment than the two of you, we need RNP/Phys1/Schneibo explaining why Tinfoil Hat Science should prevail over the contents of this article, now that would be some great entertainment, not the two of you.

The Rguy could perhaps weave an entertaining narrative about how Rotation Curves are the DEFINING EVIDENCE for the presence of Dark Matter of all the galaxies anywhere in the Universe as quoted from his handpicked authors, he could then provide a link to some pretty pics over which his favorite authors have airbrushed some purple smudges as the conclusive EVIDENCE.

Then of course there is Schneibo & his pictures of Balck Holes which he continues to keep all to himself. C'mon Schneibo, we want a Christmas present.......Pretty please?.......at least by Christmas?

Arginx
1 / 5 (7) Dec 19, 2016
This article is worth... horse SHIT... or even less.
We don't know what DM is, but THEY know if ..
>If two dark matter particles collide, they can annihilate and produce a signature of gamma-ray photons.

WHERE IS PROOF of this assumption?
Also whole conclusions about this 'research' is stricte childish.
TopJimmy
4.6 / 5 (9) Dec 19, 2016
What? I thought the current scientific community was all in a on a big lie. Why would they say something that contradicts dark matter? Oh wait, they are real scientists that do research and are willing to present their research even if it may contradict current theories. Basically the oposite of many on here that have it all figured out already.
Benni
2.3 / 5 (6) Dec 19, 2016
>If two dark matter particles collide, they can annihilate and produce a signature of gamma-ray photons.


How do you know this? Do the testing yourself & that's how you found out? You'd be the first to isolate something no one else has isolated & collide them together to produce the signature you claim.
Kron
4.2 / 5 (5) Dec 20, 2016
>If two dark matter particles collide, they can annihilate and produce a signature of gamma-ray photons.


How do you know this? Do the testing yourself & that's how you found out? You'd be the first to isolate something no one else has isolated & collide them together to produce the signature you claim.


If two dark matter particles [of a particular hypothesized type] collide, they can annihilate and produce a signature of gamma-ray photons.

The signature was not present therefore the type of proposed dark matter candidate is discounted.
RNP
4.2 / 5 (10) Dec 20, 2016

@Benni
The Rguy could perhaps weave an entertaining narrative about how Rotation Curves are the DEFINING EVIDENCE for the presence of Dark Matter of all the galaxies anywhere in the Universe as quoted from his handpicked authors, he could then provide a link to some pretty pics over which his favorite authors have airbrushed some purple smudges as the conclusive EVIDENCE.


Yet another masterclass in pseudoscientific buffoonery from Benni, the self appointed village idiot here at phys.org. Misinterpreting others words, false claims and ridiculous requests all in one short paragraph - truly impressive.

A round of applause please.
Benni
2 / 5 (8) Dec 20, 2016
The signature was not present therefore the type of proposed dark matter candidate is discounted.


I get it: "the type of candidate". So with you it comes down to a process of elimination of specific particles while never admitting the consensus debacle of the 80-95% Missing Mass Narrative.

So you imagine upon the production of some unspecified signature of gamma rays, this means you have found DM. OK, what's the gamma ray frequency you're looking for?

I oversight a gamma ray test lab as part of my job description, so if you'll kindly tell me through your SPECTROSCOPY OBSERVATIONS where in our myriads of Spectrographs this telltale frequency can be found then I can check the source. Maybe you have a frequency you'd just like to make up & challenge me to prove it isn't the frequency of DM? Yeah, go ahead & do that & really make place yourself into the class of another RNP scientific illiterate blowhard.
Benni
1.7 / 5 (6) Dec 20, 2016
@Benni


The Rguy could perhaps weave an entertaining narrative about how Rotation Curves are the DEFINING EVIDENCE for the presence of Dark Matter of all the galaxies anywhere in the Universe as quoted from his handpicked authors, he could then provide a link to some pretty pics over which his favorite authors have airbrushed some purple smudges as the conclusive EVIDENCE.


Yet another masterclass in pseudoscientific buffoonery from Benni, the self appointed village idiot here at phys.org. Misinterpreting others words, false claims and ridiculous requests all in one short paragraph - truly impressive.

A round of applause please.


Instead of spending so much of your time refuting me, why don't you turn your attention to the article itself: "No trace of dark matter in gamma-ray background".

Yeah I know Phys1, when you run out of SPIN, it's time to start another round of name calling because it's all you & Zwicky have left.

RNP
3.7 / 5 (6) Dec 20, 2016
@Benni
Thank you for the encores, but nobody really wanted them. After all, we have seen your whole performance MANY times before.
Ultron
2 / 5 (7) Dec 20, 2016
What? I thought the current scientific community was all in a on a big lie. Why would they say something that contradicts dark matter? Oh wait, they are real scientists that do research and are willing to present their research even if it may contradict current theories. Basically the oposite of many on here that have it all figured out already.


Yes, astonishingly mainstream physics keeps ignoring continuous stream of results which fail to find any direct proof for (fictional) dark matter. It is similar to situation with religious believers, it is simply impossible to give then definitive proof of non existence of God. In similar manner it is not possible to give dark matter believers definitive proof of non existence of dark matter so they rather keep believing it than to turn to real solution - updating General relativity.
Benni
2 / 5 (4) Dec 20, 2016
@Benni
Thank you for the encores, but nobody really wanted them. After all, we have seen your whole performance MANY times before.


Phys1 ........still can't come up with a narrative to refute the article? This of course is what we expect from the Tinfoil Hat pseudo-science brigade you live with in this chat room.
RNP
4.2 / 5 (5) Dec 20, 2016
@Benni
What are you talking about!!! I have at not at any point suggested the article needs refuting! You seem to be listening to a voice in your head, rather the listening to me.
tear88
1 / 5 (1) Dec 20, 2016
"No trace of dark matter in gamma-ray background"

"However, these individual sources are not enough to explain the total amount of gamma-ray photons coming from outside our Galaxy. In fact, about 75% of them are unaccounted for."

So... not dark matter, but dark gamma-ray sources? What am I misreading here?
cantdrive85
2 / 5 (8) Dec 20, 2016
So... not dark matter, but dark gamma-ray sources? What am I misreading here?

The assumption is that astrophysicists have a clue, this is dreadfully incorrect. Astrophysicist's ignorance of plasma is matched only by their knowledge of such fanciful imaginings as DM, DE, and black holes. Astrophysicists entire careers are defined by looking for that which only exists in feeble failed guesses.
nikola_milovic_378
Dec 20, 2016
This comment has been removed by a moderator.
Benni
2.3 / 5 (3) Dec 20, 2016
"No trace of dark matter in gamma-ray background"

"However, these individual sources are not enough to explain the total amount of gamma-ray photons coming from outside our Galaxy. In fact, about 75% of them are unaccounted for."

So... not dark matter, but dark gamma-ray sources? What am I misreading here?


OK, so what if 75% of gamma rays are unaccounted for? How about infrared? Ultraviolet? Radio? Xray? What % of these are unaccounted for?

Just because there are photons without a known origin, why must there be an exotic explanation as to their origin?
Benni
1 / 5 (3) Dec 20, 2016
@Benni
What are you talking about!!! I have at not at any point suggested the article needs refuting!
.....because Phys1, you've run out of narratives & catch phrases & you don't know where to go to find new ones.
thetentman
1 / 5 (3) Dec 21, 2016
DM is the exhaust from Black Holes.
gculpex
not rated yet Dec 21, 2016
DM is the exhaust from Black Holes.

waste crap...
Merrit
3 / 5 (1) Dec 22, 2016
Gravitational time dulation is the answer
gculpex
not rated yet Dec 22, 2016
Gravitational time dulation is the answer

OKAY! now that is something to talk about!
Could we be experiencing a time-dilation while in a gravity well, causing physical values to be slightly different?

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