The invisible becomes visible: Scientists may have finally seen dark matter

There is no shortage of mysteries in the universe, many of which have puzzled us throughout the ages. One of the biggest is the existence of so-called dark matter. First proposed in 1933 by Fritz Zwicky, dark matter is a theoretical type of matter that cannot be seen because it does not interact with light or any other form of electromagnetic radiation.

Nearly 100 years later, with the help of NASA’s Fermi Gamma-ray Space Telescope, researchers may have “seen” dark matter for the first time.

If this proves to be true, it will be a major development for science. Dark matter’s ability to hide in plain sight is legendary. It cannot be seen by any instrument ever made by humans because dark matter cannot emit, absorb or reflect light of any kind, and that is the way humans and all our instruments see things. This makes finding dark matter very difficult.

Tomonori Totani, a professor of astronomy at the University of Tokyo, believes that he may have succeeded where many before him had failed. in study Published November 25 in the Journal of Cosmology and Astroparticle Physics, Totani says he may have found dark matter by observing the byproduct of two dark matter particles colliding with each other.

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Key to this discovery is the theoretical existence of something called weakly interacting massive particles, or WIMPs for short. Inert particles (WIMPs) are pieces of dark matter that are larger than protons and do not interact with any other type of particle. When two weakly interacting particles (WIMPs) collide with each other, scientific theory suggests that they annihilate each other, and the resulting interaction produces gamma rays.

Totani used data from NASA’s Fermi Gamma-ray Space Telescope to find what he believes are gamma-ray emissions from these annihilation events, which, if accurate, would prove the existence of dark matter — or at least put scientists on the right track to confirming its existence.

Why is dark matter so hard to find?

NASA describes Dark matter as “the invisible glue that holds the universe together.” Dark matter is everywhere. Theories suggest that only 5% of matter is ordinary matter that you and I can see, while dark matter makes up 27% of the pie. The rest is dark energy, which is… Another puzzle This science has not yet been solved.

If there is more than five times the amount of dark matter as regular matter, why is it so difficult to see? The short answer is that dark matter does not interact with matter in a way that humans can detect using current technology.

This is not completely abnormal. Science is also having difficulty detecting black holes. Light cannot escape from a black hole, so it is impossible to see it directly. Instead, scientists have developed several ways to detect the presence of a black hole based on its effect on the surrounding environment.

Cygnus X-1 – the first black hole ever discovered – was found thanks to a so-called accretion disk. Accretion disks are swirling clouds of gas, dust, plasma and other particles that form around black holes and tend to emit enormous amounts of X-ray radiation. The researchers found those intense X-rays and concluded that they came from a black hole. in First image of a black hole The image was taken in 2019, and the visible part is the black hole’s accretion disk, not the black hole itself.

English philosopher and cleric John Michell put forward the first theory of the existence of black holes in 1783. This means that it took humanity 236 years to take a picture of a black hole, and even then, we cannot see the black hole in the picture. We only know it exists because we can see its accretion disk.

Dark matter is more difficult to detect. It does not interact with the electromagnetic spectrum at all, including visible light. Just like black holes, science has used their effect on their environment to try to prove their existence.

This phenomenon began in 1933, when it was observed by astronomer Fritz Zwicky Galaxies in the Coma cluster It was moving too fast for the amount of normal matter inside it. Zwicky concluded that there must be a second type of invisible substance that adds more gravitational force and acts as a kind of glue holding the group together.

This theory has been refined over time, as additional evidence has emerged. One example It is a gravitational lensIt is the bending of light caused by gravity. The bullet cluster is the best example of why dark matter could be the result, but this has not yet been conclusively proven.

The study’s author explains what he found

Over the decades, scientists have proposed various Potential candidates What dark matter particles actually are. One such theory is WIMP. These theoretical particles are much larger than photons and have a special property. When they collide, science predicts that they will destroy each other, resulting in a gamma-ray burst.

NASA has Short video here This shows how this would work in theory. These gamma ray emissions are what Totani believes he has discovered.

“We have detected gamma rays with a photon energy of 20 GeV (or 20 billion electron volts, which is a huge amount of energy, extending in a halo structure towards the center of the Milky Way,”) Tutani. Phys.org said. “The gamma-ray emission component closely matches the shape expected from a dark matter halo.”

There are a few things to unpack here, so I asked Totani for more information. He told me that the stars in our galaxy “are distributed in the shape of a disk, while the dark matter halo is thought to surround them in a spherical shape.” The radiation generated by the theoretical dark matter will reach the disk from its spherical location, giving Totani an idea of ​​what to look for and where to look in general.

Once he looked there, he was able to find radiation that he says was “consistent with dark matter predictions.”

In other words, the gamma rays were where they were supposed to be, at the photon energy level that science had predicted, and the emissions were in the form expected for dark matter.

Change science forever

Tutani found gamma rays where they were supposed to be and at the expected strength, so it must be dark matter, right?

Not exactly.

Although these results are promising, they do not necessarily prove the existence of dark matter. The first step would be to ask independent researchers to verify Totani’s conclusions.

Totani recognizes this and wants independent researchers to examine the data in an attempt to replicate his findings. This involves measuring gamma-ray emissions from other sources, such as dwarf galaxies, in the universe to see if there is something else that could explain his findings.

Currently, his findings cannot be easily explained by any known sources of gamma-ray emissions, but that does not mean that there are none. The data will need to be tested and retested, and researchers will need to bring back more information to verify that their findings are indeed related to dark matter.

Science will take its time on this, because if Tutani does discover dark matter, the ramifications will be enormous. He points out that the discovery of a new elementary particle not included in the current Standard Model of particle physics will have a major impact on fundamental physics theory. The discovery of dark matter would help piece together other cosmic mysteries, such as the universe The nature of dark energyThe invisible force that causes the universe to expand at an accelerating rate.

“If this is true, the true nature of dark matter, which has long been the greatest mystery in cosmology, has been revealed,” Totani said.