New theory of dark matter based on the detection of unusual X-ray radiation from galaxies

February 8, 2018, Universitaet Mainz
X-ray image of the Perseus galaxy cluster, approximately 240 million light-years away from Earth. The x-ray radiation emitted by galaxies and galaxy clusters still poses numerous puzzles to astrophysicists. In particular, it may provide clues to the nature of the mysterious dark matter. Credit: Photo courtesy of NASA

Dark matter is increasingly puzzling. Around the world, physicists have been trying for decades to determine the nature of these matter particles, which do not emit light and are therefore invisible to the human eye. Their existence was postulated in the 1930s to explain certain astronomical observations. As visible matter, like the one that makes up the stars and the Earth, constitutes just 5 percent of the universe, it has been proposed that dark matter must represent 23 percent of what is out there. But to date and despite intensive research, it has proved impossible to actually identify the particles involved. Researchers at Johannes Gutenberg University Mainz (JGU) have now presented a novel theory of dark matter, which implies that dark matter particles may be very different from what is normally assumed. In particular, their theory involves dark matter particles which are extremely light—almost one hundred times lighter than electrons, in stark contrast to many conventional models that involve very heavy dark matter particles instead.

According to common theory, must exist because otherwise stars would not continue to rotate around the center of their galaxies as they in fact do. Among the particularly favored candidates for dark matter are so-called weakly interacting massive , or WIMPs. Researchers are searching for these in the Italian Gran Sasso underground laboratory, for example. But recent scientific publications in the field of astroparticle physics are increasingly taking the view that WIMPs are unlikely to be viable prospects when it comes to dark matter. "We, too, are currently actively on the search for possible alternatives," said Professor Joachim Kopp of Mainz University.

The physicist, together with his colleagues Vedran Brdar, Jia Liu, and Xiao-Ping Want, took a closer look at the results of observations undertaken by several independent groups in 2014. The groups reported the presence of a previously undetected spectral line, with an energy of 3.5 kiloelectron volts (keV), in x-ray light from distant galaxies and galaxy clusters. This unusual x-ray radiation might offer a clue to the nature of dark matter. It has been previously pointed out that dark matter particles might decay, thereby emitting x-rays. However, Joachim Kopp's team at the Mainz-based Cluster of Excellence on Precision Physics, Fundamental Interactions and Structure of Matter (PRISMA) is taking another approach.

X-ray radiation produced by the annihilation of dark matter

The PRISMA researchers propose a scenario in which two dark matter particles collide, resulting in their mutual annihilation. This is analogous to what happens, for instance, when an electron meets with its antiparticle, a positron. "It has long been assumed that it would not be possible to observe such annihilation of dark matter if it were made of particles that light," explained Kopp. "We have subjected our new model to scrutiny and have compared it with experimental data, and it all fits together much better than in the case of older models."

According to Kopp's model, would be fermions with a mass of only a few kiloelectron volts, frequently called sterile neutrinos. Such lightweight dark matter is usually considered problematic because it makes it difficult to explain how galaxies could have been formed. "So far, we have been able to deal with these concerns," explained Kopp. "Our model provides an elegant way out." The supposition that the annihilation of dark matter is a two-step process is of crucial importance in this context: during the initial stage of the process, an intermediate state is formed, which later disintegrates into the observed x-ray photons. "The results of our calculations show that the resulting x-ray signature correlates closely with the observations and thus offers a novel explanation for these," added Kopp.

At the same time, the new itself is so general that it will offer an interesting starting point for the search for dark even if it turns out that the discovered in 2014 has a different origin. Theoretical and experimental physicists at JGU are currently working on the proposed ESA mission e-ASTROGRAM, which aims at analyzing astrophysical with previously unachieved accuracy.

Explore further: New theory on the origin of dark matter

More information: Vedran Brdar et al. X-Ray Lines from Dark Matter Annihilation at the keV Scale, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.061301 , https://arxiv.org/abs/1710.02146

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novasp9
2.3 / 5 (3) Feb 08, 2018
It is the obsession with "particles", ad hoc mythical subatomic particles, that is the cause of the decades old failure to solve the dark matter enigma.

Black holes are a far, far better candidate and 100s of billions have already been observed or inferred. They would need to be primordial black holes of stellar mass. Highly fundamental objects that are as much a part of nature as protons and electrons.
dogbert
2 / 5 (4) Feb 08, 2018
After more than 80 years looking for dark matter, it is a good bet that discovering the reason(s) our observations do not match our observations is not going to happen any time soon.

Nomenclature of the observed anomalies, always "dark matter", insures that we will continue to focus on mass of some type as the answer to the anomalies.
Osiris1
1 / 5 (3) Feb 08, 2018
The thing about really small particles is that there is strong likelihood that there are and immense number of them. Another thing is that space may be cellular in nature as well. There is a truly great deal of space, hiding in plain sight right in front of us.
cantdrive85
1 / 5 (8) Feb 08, 2018
The plasma ignoramuses refusal to understand plasma/electric discharges will require them to continue down the dead-end path of magical faerie dust to their answer of all things to which they are ignorant. If they cannot move passed their pre-spaceage beliefs of their hypothetical "ideal ionized gases" which their entire edifice is based, they will continue to conjure up magical faerie dust/energy to explain away their utter failure of describing cosmic phenomena.
Benni
1.4 / 5 (10) Feb 08, 2018
It still hasn't dawned on these self appointed geniuses, that first you need to find the very first DM particle before it's origin can be ascertained, I guess they just forgot.
eric96
1 / 5 (4) Feb 08, 2018
"Such lightweight dark matter is usually considered problematic because it makes it difficult to explain how galaxies could have been formed."

Therein is the fallacy that has fooled thousands of researchers.
It is perfectly normal to discover something and then discover a bigger mystery.
Let the facts speak for themselves, stop trying to fit everything into a universal model.
Do you have any ideal how arrogant that is.
Continued further below...
eric96
1 / 5 (4) Feb 08, 2018
The way I think about it, think of every galaxy as having all the after math of the big bang, so very dense field of particles all traveling at the speed of light. At this point in time, a galaxy is merely a bunch of particles traveling together (not formally a galaxy). Particle fields collide with one another and this accelerates universal evolution (mass starts to be factor, stars are born, and x known time after black holes are born. At this point, there is no formal galaxy yet, but as fields of particles ( informal galaxies ) keep colliding and black holes create more and more dark matter, merely fields of particles now cling to these dark matter halos (formal galaxy formation begins). Further collisions and galactic evolution eventual leads to spiral galaxies which come later in evolution. The spin of a spiral galaxy is merely a magic show orchestrated by dark matter which makes it look more complicated then it really is, but exacting its beauty.
Mimath224
2 / 5 (2) Feb 08, 2018
Hmmm, If DM particles decay into x-rays and if the figure of 23% DM is anywhere near the truth (assuming DM particles exist at all, that is) wouldn't there be a lot more of the 'unusual x-rays' and a lot more discussion by mainstream scientists? If there is such a decay is there the evidence that a lot more of DM was out there a few billion years ago than what there is now? Wouldn't 'more DM' exhibit some kind of gravitational restraint on galaxy, star etc. formation way back then? Those are my questions as a layman so I stand to be corrected by someone more professional.
NoStrings
4 / 5 (4) Feb 08, 2018
Just like that - unexplained 3.5kev soft X-ray. What could it be? Wait wait, it must be little dwarf dark matter particles giving a ghost! How? Who cares, aren't you excited about our dark matter discovery?!? Or was it dim matter? Or maybe dumb matter? Any more alternatives? Whatever, we claim we found it. Kudos, my friends; it will do for a master thesis.
Mimath224
1 / 5 (2) Feb 08, 2018
Just like that - unexplained 3.5kev soft X-ray. What could it be? Wait wait, it must be little dwarf dark matter particles giving a ghost! How? Who cares, aren't you excited about our dark matter discovery?!? Or was it dim matter? Or maybe dumb matter? Any more alternatives? Whatever, we claim we found it. Kudos, my friends; it will do for a master thesis.

Quite, I think someone is trying to justify their grant or whatever.
Hyperfuzzy
1 / 5 (2) Feb 09, 2018
I think you are talking about the infinite field of each charge and is unique. We call the center of this field charge! Yes, the field is invisible, we see only the wrinkle in the field, or more like a shimmer! That's it. Particles do not exist, space is only conceptual, all that exists are these diametrical fields, immortal.
dirk_bruere
1 / 5 (1) Feb 09, 2018
Seems that there may be no single explanation for DM, but it may be a symptom of several different things
Hyperfuzzy
1 / 5 (2) Feb 13, 2018
We still have faith in the nonsense of the standard model, QM, and GR? Only the infinite fields! They are immortal, never created or destroyed. An infinite set of Diametrical Fields, whose centers we call charge! When they move we see them shimmer.
Hyperfuzzy
1 / 5 (2) Feb 13, 2018
In addition, it would be quite strange if normal neutrinos would have rest mass energy in sub electronvolt range and sterile neutrinos (lacking features) would be much heavier - isn't it true? The common sense is what the theoretical physics is often lacking.

Other than that we can observe gradual convergence of physical models of dark matter from WIMPs in GeV range to somewhat more realistic scenarios - but this convergence is slow, because it adheres on existing models, being gradualist and depending on progress in experiments - not actual understanding of dark matter subject. We tax payers would save lotta money wasted in futile research, if physicists wouldn't behave like gregarious sheep driven by occupation and groupthink.

Neutrino is the wrinkle in the fields of the dancing centers as they separate.
Benni
1 / 5 (3) Feb 13, 2018
Seems silly doesn't it? To assume the reason for the existence of something is because it hasn't yet been found, but who knows, hope springs eternal, maybe someday they'll come to the realization that when they're looking into that full length body mirror that the image they see is not 80% MISSING & it really is their BMI that creates that pop-up on the weight scale.

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