Astronomers may have first been able to shed light on the nature of dark matter – a strange substance, the existence of which scientists began to suspect even 70 years ago, but still catch the signal which could not be anyone. More precisely, could shed light very dark matter in the form of a small number of photons. If so, the scientists will soon realize what particles it is and what hypotheses must be discarded.
Dark matter and dark the fact that no light radiates and manifests itself only indirectly – by excessive attraction of stars in galaxies so the bending of light – two effects associated with its gravitational influence. On the role of the media, scientists offer different matter, is not yet known to science exotic particles, such as the so-called WIMPs – weakly interacting massive particles, sterile neutrinos and others.
Astronomers led by Oleg Ruchayskogo from the Federal Polytechnic School of Lausanne and with the support of Leiden University, analyzing the X-rays of two objects – our neighboring galaxy Andromeda and Perseus cluster of galaxies, recorded signal, which can be attributed to the particles – carriers of dark matter.
In their work researchers conducted a broad analysis of data obtained by the space X-ray Observatory XMM-Newton, who was watching these objects.
With a large amount of recorded data, the researchers were able to capture the subtle excess of X-rays in a narrow section spectrum – 3.5 keV.
It was immediately clear that this excess – an excess of photons produced at birth of any particles.
Scientists believe that these photons can be produced in the decay of sterile neutrinos – one of the candidates in the media dark matter.
«Observations of the Andromeda galaxy using the XMM-Newton satellite carried out not by us. All these data are available in the public domain. We chose from an array of data those observations, which were of interest to us – Andromeda, Perseus and the Milky Way, “- said” Gazeta.ru “Oleg Ruchaysky.
According to him, in one of the bands was detected splash – the scientists saw a few hundred extra photons whose existence can not be explained with the help of astrophysical models.
«This is a very weak signal. This excess above the background just 1-1.5%. Failed to notice them because the observations were very long, “- he added.
Ruchaysky said that notice before the excess was not possible because the length of previous observations did not exceed hundred thousand seconds.
Now the researchers took all the available observations from the center of Andromeda and Perseus. And only because of this they saw the three signals, the statistical significance of which is 3σ.
«There is always some unaccounted mathematical error. For us it is important that we see the signal not only in the Andromeda Galaxy, but in the Perseus Cluster. And it is farther from us than the Andromeda. Therefore, this signal has a slight red shift – a few less energy, “- said Oleg Ruchaysky. According to him, this shift corresponds to a distance from the Milky Way.
Finally, the researchers “looked” at the center of the Milky Way and saw the same signal. There he is in nominal position – the center of the Milky Way from us is not biased. Knowing what signal in Andromeda, the scientists were able to calculate the signal to be in the Milky Way.
And they got it.
In addition to of similar studies, but in relation to other objects, astronomers conducted at Harvard, as well as Maxim Markevitch of IKI, and they have achieved similar results.
Another important factor that confirms the origin of dark matter, are measuring the spatial distribution. In the case of the Perseus Cluster is large and takes up the sky area of a radius of about two angular degrees. This is a great and interesting cluster, scientists are studying it very actively “in X-rays.” There are observations at different distances from the center of the cluster – the astronomers looked in the central region, with shifts and up to the brim.
«You can split observations into groups according to how they are located from the center. It can be seen that the intensity of the line decreases. It is visible in each group separately – have a low statistical significance.
At the same time it is clear that it decreases as we would expect to reduce the signal of dark matter.
However, the statistical significance is not sufficiently high, something to say for sure, “- said Ruchaysky.
Researchers have tried to find the signal in the Andromeda Galaxy is the center, and they did not succeed – the signal was too weak to see it with the machine XMM-Newton.
Initially, scientists have been searching for sterile neutrinos decay, but even if found signal is confirmed, it does not say what kind of particle breaks.
«This tells us that there is some kind of particle. It’s light.
Her weight 7 GeV. But what is a particle, we know we can not. We can eliminate a lot of options, such as WIMP – it’s too easy. But candidates for such a signal is very much “- said Oleg Ruchaysky.
According to him, how many photons will decaying sterile neutrinos, determined by the time of his life. Now researchers believe that it is longer than the 10 26 and 10 27 seconds. And the results of observations confirm this yet.
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