The search for dark matter—axions have ever-fewer places to hide

February 15, 2018, The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
The distribution of dark matter (colored in blue) in six galaxy clusters, mapped from the visible-light images from the Hubble Space Telescope. (Source: NASA, ESA, STScI, and CXC) Credit: NASA, ESA, STScI, and CXC

If they exist, axions, among the candidates for dark matter particles, could interact with the matter comprising the universe, but at a much weaker extent than previously theorized. New, rigorous constraints on the properties of axions have been proposed by an international team of scientists.

The latest analysis of measurements of the electrical properties of ultracold neutrons, published in the scientific journal Physical Review X, has led to surprising conclusions. On the basis of data collected in the Electric Dipole Moment of Neutron (nEDM) experiment, an international group of physicists demonstrated that axions, hypothetical particles that may comprise cold , would have to comply with much stricter limitations than previously believed with regard to their mass and manners of interacting with . The results are the first laboratory data imposing limits on the potential interactions of axions with nucleons (i.e. protons or neutrons) and gluons (the particles bonding quarks in nucleons).

"Measurements of the electric dipole moment of neutrons have been conducted by our international group for a good dozen or so years. For most of this time, none of us suspected that any traces associated with potential particles of dark matter might be hidden in the collected data. Only recently, theoreticians have suggested such a possibility and we eagerly took the opportunity to verify the hypotheses about the properties of axions," says Dr. Adam Kozela (IFJ PAN), one of the participants in the experiment.

Dark matter was first proposed to explain the movements of stars within galaxies and galaxies within galactic clusters. The pioneer of statistical research on star movements was the Polish astronomer Marian Kowalski. In 1859, he noticed that the movements of nearby stars could not be explained solely by the movement of the sun. This was the first observational evidence suggesting the rotation of the Milky Way. Kowalski is thus the man who "shook the foundations" of the galaxy. In 1933, the Swiss astronomer Fritz Zwicky went one step further. He analyzed the movements of structures in the Coma galaxy cluster using several methods. He then noticed that they moved as if there were a much larger amount of matter in their surroundings than that observed by astronomers.

Astronomers believe there should be almost 5.5 times as much dark matter in the universe as ordinary matter, as background microwave radiation measurements suggest. But the nature of dark matter is still unknown. Theoreticians have constructed many models predicting the existence of particles that are more or less exotic, which may account for dark matter. Among the candidates are axions. These extremely light particles would interact with ordinary matter almost exclusively via gravity. Current models predict that in certain situations, a photon could change into an , and after some time, transform back into a photon. This hypothetical phenomenon is the basis of the famous "lighting through a wall" experiments. These involve directing an intense beam of laser light onto a thick obstacle, and observing those photons that change into axions that penetrate the wall. After passing through, some of the axions could become photons again, with features exactly like those originally directed at the barrier.

Experiments related to measuring the of neutrons have nothing to do with photons. In experiments conducted for over 10 years, scientists measured changes in the frequency of nuclear magnetic resonance (NMR) of neutrons and mercury atoms in a vacuum chamber in the presence of electric, magnetic and gravitational fields. These measurements enabled the researchers to draw conclusions about the precession of neutrons and mercury atoms, and consequently on their dipole moments.

Theoretical works have appeared in recent years that envisage the possibility of axions interacting with gluons and nucleons. Depending on the mass of the axions, these interactions could result in smaller or larger disturbances with the character of oscillations of dipole electrical moments of nucleons, or even whole atoms. The predictions meant that experiments conducted as part of the nEDM cooperation could contain valuable information about the existence and properties of potential particles of dark .

"In the data from the experiments at PSI, our colleagues conducting the analysis looked for frequency changes with periods in the order of minutes, and in the results from ILL—in the order of days. The latter would appear if there was an axion wind, that is, if the axions in the near Earth space were moving in a specific direction. Since the Earth is spinning, at different times of the day our measuring equipment would change its orientation relative to the axion wind, and this should result in cyclical, daily changes in the oscillations recorded by us," explains Dr. Kozela.

The results of the search turned out to be negative. No trace of the existence of axions with masses between 10-24 and 10-17 electron volts were found (for comparison: the mass of an electron is more than half a million electron volts). In addition, the scientists managed to tighten the constraints imposed by theory on the interaction of axions with nucleons by 40 times. In the case of potential interactions with gluons, the restrictions have increased more than 1000-fold. So if axions do exist, in the current theoretical models, they have fewer places to hide.

Explore further: A new bound on axions

More information: C. Abel et al, Search for Axionlike Dark Matter through Nuclear Spin Precession in Electric and Magnetic Fields, Physical Review X (2017). DOI: 10.1103/PhysRevX.7.041034

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Benni
1.3 / 5 (12) Feb 15, 2018
"The results of the search turned out to be negative. No trace of the existence of axions with masses between 10-24 and 10-17 electron volts were found. So if axions do exist, in the current theoretical models, they have fewer places to hide."

It leaves me to wondering, why then do these cosmologists keep putting up pictures of galaxies surrounded by airbrushed blue halos in an attempt to fool unsuspecting casual readers that these are actual observational pics of real Dark Matter?

The progenitors of these cosmic fairy tale narratives are so out of touch with the real world of Nuclear Physics that they refuse to retouch their airbrushed pics & drop the representative DM blue halos, halos for which lack of axion data drives just one more a huge spike into the coffin lid of the DM Narrative.

Hey, Fritz Zwicky fans, welcome to the 21st century.
mackita
2 / 5 (4) Feb 15, 2018
Axions are last scream/swan song of classical physics paradigms in search for dark matter I hope. The physicists are looking for well defined particles but in dense aether model the dark matter is merely an analogy of ripples at the surface of ocean. You can see many waves there actually - but each one is different. If we would look for some distinct waves in their spectrum, we would find no peak, despite that whole water surface is heavily curved and full of some particles.
There are also conceptual problems with definition of axions, which were proposed for solving CP problem is nuclear chromodynamics. Nuclear processes run at much higher energies, than the sparse dark matter between galaxies. I dunno what physicists expect from such a models - this is like to search for glueballs in free cosmic space. The dumb abstract approach to physics strikes here again.
mackita
2 / 5 (4) Feb 15, 2018
No trace of the existence of axions with masses between 10-24 and 10-17 electron volts were found.
Neutrinos are way heavier than that and they have distinct lepton charge - yet they already oscillate due to quantum fluctuations of vacuum. These oscillations can be imagined like less or more periodic dissolving of particle (or at least its pilot wave) in density fluctuations of vacuum (which have energy in range of 7.0 × 10−4 eVm which is typical energy of CMBR photons). If the neutrinos (which have rest mass in range 0.01 - 0.2 eV) are already affected by it, what we could expect for axions? Such a lightweight particles would be completely blurred across whole energy density spectrum by quantum fluctuations of vacuum. Sometimes the healthy common sense is missing in theoretical physics.
Hyperfuzzy
2.3 / 5 (3) Feb 15, 2018
Excuse me, one does not Easter Egg as Science!
SlartiBartfast
3.7 / 5 (3) Feb 15, 2018
Hey, Fritz Zwicky fans, welcome to the 21st century.


Fritz Zwicky once jumped, naked, into a frozen-over pond to rescue a drowning puppy. Truly a hero.
Turgent
3 / 5 (2) Feb 15, 2018
Notable quote: "They are spherical bastards." F. Zwicky They look the same from wherever you look at them.
mackita
2 / 5 (4) Feb 15, 2018
Zwicky was mostly right, as he always guessed, that the Hubble red shift results from scattering of light - not from metric expansion of space-time - after all, in similar way, like Hubble himself. He was co-founder of correct explanation too, as he also observed many dark matter effects first. He just couldn't guess, which particles should be responsible for this scattering. He believed, that the red shift results from scattering of light by free electrons and another charged particles from interstelllar space. But the scattering of light by massive particles differs from scattering of light by dark matter fluctuations in many aspects - actually it's working in quite opposite way in many extents. The massive particles tend to me much smaller but also less temporary than light waves. Dark matter fluctuations have it opposite: they're quite big but shortliving. The disappear faster than the light wave can pass across them - so that they tend to break symmetry of Maxwell equations.
mackita
2 / 5 (4) Feb 15, 2018
Therefore the dark matter fluctuations have less or more pronounced magnetic monopole character - they form weak underdeveloped monopoles, so-called anapoles. This aspect of behavior they have in common with axions proposed. If magnetic monopoles exist then there is a symmetry in Maxwell's equations where the electric and magnetic fields can be rotated into each other with the new fields still satisfying Maxwell's equations. Luca Visinelli showed that the duality symmetry can be carried over to the axion-electromagnetic theory as well. A term analogous to the one that would be added to Maxwell's equations to account for axions also appears in theoretical models for topological insulators. This term leads to several interesting analogies at the interface between topological and normal insulators.
Benni
1 / 5 (6) Feb 15, 2018
Notable quote: "They are spherical bastards." F. Zwicky They look the same from wherever you look at them.


.........he also directed this statement right at Einstein at a symposium they were both attending in the 30's.

Zwicky got ticked off that Einstein wouldn't meet with him at that particular symposium. Zwicky then went off on a name calling rant using the "spherical bastard" quip right in the middle of another person's presentation & shutting down the whole floor, the same kind of conduct that goes on in this chatroom after the Stumpies, Schneibos & Jonesies run out of FACTS.

Yeah, Zwicky, the genius who declared that rockets wouldn't work in outer space because rocket exhaust needed the presence of Earth's atmosphere to push against to create forward thrust. This is the guy who is an icon by the DM Enthusiasts who live here but who, unlike Einstein, have never seen a Differential Equation they could solve, we at least know what they all have in common.

mackita
2.3 / 5 (3) Feb 15, 2018
Yeah, Zwicky, the genius who declared that rockets wouldn't work in outer space because rocket exhaust needed the presence of Earth's atmosphere
Every genius has its own limits, Einstein for example believed in orgone and participated in its "research" for some time. The difference of geniuses from trolls isn't the absence of mistakes, but the fact that their mistakes don't influent their main job work and they're able to learn from them. Similarly to Einstein's orgone, the Zwicky's faux-pass also represented just an episode in Zwicky's life: he wasn't constructor of rockets after all.
Benni
1 / 5 (4) Feb 15, 2018
the Zwicky's faux-pass also represented just an episode in Zwicky's life: he wasn't constructor of rockets after all.


He's also the one who pushed hard for the Tired Light Theory. Yet another one he lost out on that made him such a laughing stock in the 1930's scientific community.
mackita
1.7 / 5 (6) Feb 15, 2018
IMO the tired light theory was most insightful contribution of Zwicky to physics. But when you're two steps ahead of the crowd, you're a crackpot.
Steelwolf
5 / 5 (2) Feb 15, 2018
Actually, here is a good candidate for Axion; The photons were passed through an ultra-cold cloud of rubidium atoms and the photons were emitted in pairs and triplets. Not only were they strongly bound, they lost much of their speed AND took on effective mass.

https://phys.org/...tum.html

So, it is Looking like the idea of Ultracold condensed photons forming their own strongly bound particles is a reality after all. I have considered similar setups and approaches to this problem myself but had no access to such equipment to be able to run such experiments, so it is fun to see someone else having similar ideas, being able to do the research and putting the papers out there.

I wonder how many axions it takes to become a quark, or gluon for that matter. This becomes more interesting by the day! An Optical State may just be that elusive Axion they been looking for, and here they are making them and watching them interact.
Benni
1 / 5 (3) Feb 15, 2018
IMO the tired light theory was most insightful contribution of Zwicky to physics. But when you're two steps ahead of the crowd, http://www.azquot...-60.jpg.


..........then you don't understand what the Tired Light Theory was about that Zwicky had concocted. Have you studied it? I have looked at it, it's dumb. No wonder so many reputable scientists of that era had so much fun laughing at the guy.
mackita
3.7 / 5 (6) Feb 15, 2018
No wonder so many reputable scientists of that era had so much fun laughing at the guy.
IMO it's OK - they usually laugh at you first...
Benni
1 / 5 (6) Feb 15, 2018
No wonder so many reputable scientists of that era had so much fun laughing at the guy.


IMO it's OK - they https://i.imgur.com/f9OnP3kl.jpg first...
.......but Zwicky didn't WIN. His reckless argument won him the disdain of the entire sceince community often referring to him as Zany Zwicky, he had other problems too.
malapropism
3 / 5 (4) Feb 15, 2018
@Steelwolf
Actually, here is a good candidate for Axion; The photons were passed through an ultra-cold cloud of rubidium atoms and the photons were emitted in pairs and triplets. Not only were they strongly bound, they lost much of their speed AND took on effective mass.

https://phys.org/...tum.html ...

That's an interesting article. The theory the researchers propose seems to indicate that a smaller number of atoms might cause a stronger interaction (fewer atoms for the photons to "skip across" so more photons have to interact with the same atom). That should be testable, although possibly quite difficult, using the "fountain atomic clock"-type technology to reduce the number of cooled atoms down to (theoretically) one; of course, that technology normally uses Cesium (or Strontium) and this experiment used Rubidium but the principle ought to hold I imagine?
mackita
3.7 / 5 (3) Feb 16, 2018
Actually, here is a good candidate for Axion; The photons were passed through an ultra-cold cloud of rubidium atoms
Except that this effect is fully explained by quantum mechanics... And the photons condense because of material environment (boson condensate) in which they're spreading - not because some vacuum states (dark matter particles the less).
cantdrive85
1.7 / 5 (6) Feb 16, 2018
The search for dark matter—axions have ever-fewer places to hide

Not a problem, just send more money and we'll keep looking...
Benni
1.5 / 5 (8) Feb 16, 2018
The search for dark matter—axions have ever-fewer places to hide

Not a problem, just send more money and we'll keep looking...


.......and not only have the corners gotten smaller in which to hide this cosmic fairy dust fantasy, these cosmologist geniuses may soon uncover the fact that fairies don't exist.
milnik
1 / 5 (2) Feb 20, 2018
The existence of dark matter invents people without any level of awareness and knowledge of the structure of the universe. All possible movements of celestial bodies, all the way to the clusters of galaxies, can be explained, knowing the law, that the sum of the kinetic and potential energy between the two bodies is constant and, when moving, these two energies are exchanged, by law, using the corrected Kepler zones. All the systems of celestial bodies move around the center of mass, as well as the galaxy, but science is not capable of correcting Kepler's laws and inventing stupid and unnatural theories, some "Frankenstein particles" in order to hide their stupidity and ignorance.
milnik
1 / 5 (2) Feb 20, 2018
Aether and matter form gravity, which causes movement of the body and their collection all the way to the black hole. And magnetism is the one that can not appear without Aether, and its basis is gluon. If this is known, there will be millions of fabrications and nebulosities. What axions and what kind of stupidity. !!

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