Scientists are looking for dark matter that has not interacted with light for decades but covers the entire universe. All clues from the universe are explored in detail to find dark matter. But no concrete evidence of dark matter has been found so far. In 2014, researchers caught a mysterious signal from a galaxy located relatively close to Earth. Scientists have thought for years that this mysterious signal is evidence of dark matter. Some models of dark matter say that dark matter particles gradually degrade and turn into ordinary matter, while weak photons that appear during this degradation can be detected by X-ray telescopes. An X-ray emission captured in 2014 was therefore considered evidence of dark matter. However, a new study on the mysterious signal showed that this is not the case. Scientists thought that this emission, called the “3.5 keV line”, was due to sterile neutrinos that are candidates for dark matter. Sterile neutrinos are hypothetical particles related to neutrinos whose mass is very close to zero. Sterile neutrinos, which are part of the neutrinos that are thought to occur as a result of nuclear reactions, are thought to be actually dark matter since sterile neutrinos cannot be explained by the Standard Model of particle physics. A recent study at the University of Michigan led to the discovery that the mysterious emission, called the 3.5 keV line, was not caused by sterile neutrinos. In the study, the data collected by the XMM-Newton Space X-Ray Telescope from the Milky Way for the last 20 years were examined. When the researchers analyzed 20 years of data, they found evidence that this signal did not come from dark matter. Researchers searched for different 3.5 keV lines in the universe to find that the signal does not belong to dark matter. Although we are in the dark matter ring of the Milky Way, no data on the 3.5 keV line was found. This showed that the 3.5 keV line was not caused by dark matter. However, these results may not mean that sterile neutrinos will not be dark matter. The researchers think there may be differences sterile neutrino particles that do not give the same signal. Although the 3.5 keV line signals were not found in the research, the technique developed by the researchers to find dark matter may provide the presence of dark matter in future studies. One of the authors of the article about the study, Ben Safdi, a professor of physics from the University of Michigan, said that the study brought a brand new approach to the discovery of dark matter, although it wasted a clue about dark matter. Kerstin Perez from the University of Michigan, who did not participate in the study, says there are many other areas of the universe with sterile neutrinos, and that it can be looked for to find dark matter. Perez said dark matter is of different density in different parts of the universe. In contrast to the previous studies, the researchers tried to look at the dark matter ring of the Milky Way in the dark matter study. This new perspective expresses a new horizon in the world of science for the discovery of dark matter.
