Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cosmic x-rays may provide clues to the nature of dark matter

09.02.2018

Physicists propose a new theory of dark matter based on the detection of unusual x-ray radiation from galaxies

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.


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.

photo/©: Photo courtesy of NASA

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, dark matter 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 particles, 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, dark matter particles 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 model itself is so general that it will offer an interesting starting point for the search for dark matter even if it turns out that the spectral line 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 x-ray radiation with previously unachieved accuracy.

Image:
http://www.uni-mainz.de/bilder_presse/08_physik_thep_dunkle_materie_roentgen.jpg
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.
photo/©: Photo courtesy of NASA

Publication:
Vedran Brdar et al.
X-ray lines from dark matter annihilation at the keV Scale
Physical Review Letters 120:6, 061301, 5 February 2018
DOI: 10.1103/PhysRevLett.120.061301
https://doi.org/10.1103/PhysRevLett.120.061301
https://arxiv.org/abs/1710.02146

Contact:
Professor Dr. Joachim Kopp
Theoretical High Energy Physics (THEP)
Institute of Physics
Johannes Gutenberg University Mainz
55099 Mainz, GERMANY
phone +49 6131 39-26117
e-mail: jkopp@uni-mainz.de
http://www.staff.uni-mainz.de/jkopp/

Related links:
http://www.prisma.uni-mainz.de/846.php – Professor Joachim Kopp, PRISMA Professor for Theoretical Particle Physics ;
http://www.prisma.uni-mainz.de – Precision Physics, Fundamental Interactions and Structure of Matter (PRISMA) Cluster of Excellence

Weitere Informationen:

http://www.uni-mainz.de/presse/aktuell/3620_ENG_HTML.php – press release "Mainz physicists propose a new method for monitoring nuclear waste" (6 Dec. 2017) ;
http://www.uni-mainz.de/presse/aktuell/2360_ENG_HTML.php – press release "New theory on the origin of dark matter" (8 Aug. 2017)

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht The magic wavelength of cadmium
16.09.2019 | University of Tokyo

nachricht Tomorrow´s coolants of choice
16.09.2019 | Helmholtz-Zentrum Dresden-Rossendorf

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

Im Focus: The working of a molecular string phone

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.

This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.

Im Focus: Milestones on the Way to the Nuclear Clock

Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.

If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...

Im Focus: Graphene sets the stage for the next generation of THz astronomy detectors

Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy.

Beyond superconductors, there are few materials that can fulfill the requirements needed for making ultra-sensitive and fast terahertz (THz) detectors for...

Im Focus: Physicists from Stuttgart prove the existence of a supersolid state of matte

A supersolid is a state of matter that can be described in simplified terms as being solid and liquid at the same time. In recent years, extensive efforts have been devoted to the detection of this exotic quantum matter. A research team led by Tilman Pfau and Tim Langen at the 5th Institute of Physics of the University of Stuttgart has succeeded in proving experimentally that the long-sought supersolid state of matter exists. The researchers report their results in Nature magazine.

In our everyday lives, we are familiar with matter existing in three different states: solid, liquid, or gas. However, if matter is cooled down to extremely...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

 
Latest News

Too much of a good thing: overactive immune cells trigger inflammation

16.09.2019 | Life Sciences

Scientists create a nanomaterial that is both twisted and untwisted at the same time

16.09.2019 | Materials Sciences

Researchers have identified areas of the retina that change in mild Alzheimer's disease

16.09.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>