Nav: Home

A new candidate for dark matter and a way to detect it

June 10, 2019

Two theoretical physicists at the University of California, Davis have a new candidate for dark matter, and a possible way to detect it. They presented their work June 6 at the Planck 2019 conference in Granada, Spain and it has been submitted for publication.

Dark matter is thought to make up just over a quarter of our universe, with most of the rest being even-more mysterious dark energy. It cannot be seen directly, but dark matter's presence can be detected because its gravity determines the shape of distant galaxies and other objects.

Many physicists believe that dark matter is made up of some particle yet to be discovered. For some time, the favorite candidate has been the Weakly Interacting Massive Particle or WIMP. But despite years of effort, WIMPs have so far not shown up in experiments designed to detect them.

"We still don't know what dark matter is," said John Terning, professor of physics at UC Davis and coauthor on the paper. "The primary candidate for a long time was the WIMP, but it looks like that's almost completely ruled out."

An alternative to the WIMP model of dark matter calls for a form of "dark electromagnetism" including "dark photons" and other particles. Dark photons would have some weak coupling with "regular" photons.

In their new paper, Terning and postdoctoral researcher Christopher Verhaaren add a twist to this idea: a dark magnetic "monopole" that would interact with the dark photon.

In the macroscopic world, magnets always have two poles, north and south. A monopole is a particle that acts like one end of a magnet. Monopoles are predicted by quantum theory, but have never been observed in an experiment. The scientists suggest that dark monopoles would interact with dark photons and dark electrons in the same way that theory predicts electrons and photons interact with monopoles.

A new way to detect dark matter

And that implies a way to detect these dark particles. The physicist Paul Dirac predicted that an electron moving in a circle near a monopole would pick up a change of phase in its wave function. Because electrons exist as both particles and waves in quantum theory, the same electron could pass on either side of the monopole and as a result be slightly out of phase on the other side.

This interference pattern, called the Aharonov-Bohm effect, means that an electron passing around a magnetic field is influenced by it, even if it does not pass through the field itself.

Terning and Verhaaren argue that you could detect a dark monopole because of the way it shifts the phase of electrons as they pass by.

"This is a new type of dark matter but it comes with a new way to look for it as well," Terning said.

Electron beams are relatively easy to come by: electron microscopes were used to demonstrate the Aharonov-Bohm effect in the 1960s, and electron beam technology has improved with time, Terning noted.

Theoretically, dark matter particles are streaming through us all the time. To be detectable in Terning and Verhaaren's model, the monopoles would have to be excited by the Sun. Then they would take about a month to reach Earth, traveling at about a thousandth of the speed of light.

On the other hand, the predicted phase shift is extremely small -- smaller than that needed to detect gravity waves, for example. However, Terning noted that when the LIGO gravity wave experiment was first proposed, the technology to make it work did not exist --instead, technology caught up over time.
-end-
The work was supported by a grant from the U.S. Department of Energy.

University of California - Davis

Related Dark Matter Articles:

Does dark matter annihilate quicker in the Milky Way?
Researchers at the Tata Institute of Fundamental Research in Mumbai have proposed a theory that predicts how dark matter may be annihilating much more rapidly in the Milky Way, than in smaller or larger galaxies and the early Universe.
Origin of Milky Way's hypothetical dark matter signal may not be so dark
A mysterious gamma-ray glow at the center of the Milky Way is most likely caused by pulsars.
A new look at the nature of dark matter
A new study suggests that the gravitational waves detected by the LIGO experiment must have come from black holes generated during the collapse of stars, and not in the earliest phases of the Universe.
Dark matter may be smoother than expected
Analysis of a giant new galaxy survey, made with ESO's VLT Survey Telescope in Chile, suggests that dark matter may be less dense and more smoothly distributed throughout space than previously thought.
Supercomputer comes up with a profile of dark matter
In the search for the mysterious dark matter, physicists have used elaborate computer calculations to come up with an outline of the particles of this unknown form of matter.
Mapping the 'dark matter' of human DNA
Researchers from ERIBA, Radboud UMC, XJTU, Saarland University, CWI and UMC Utrecht have made a big step towards a better understanding of the human genome.
Reconciling dwarf galaxies with dark matter
Dwarf galaxies are enigmas wrapped in riddles. Although they are the smallest galaxies, they represent some of the biggest mysteries about our universe.
Did gravitational wave detector find dark matter?
When an astronomical observatory detected two black holes colliding in deep space, scientists celebrated confirmation of Einstein's prediction of gravitational waves.
Dark matter does not contain certain axion-like particles
Researchers at Stockholm University are getting closer to corner light dark-matter particle models.
SDU researchers present a new model for what dark matter might be
There are indications that we might never see the universe's mysterious dark matter.

Related Dark Matter Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...