Russian scientists have understood how to create dark matter of neutrinos

© Photo : NASA/DOE/Fermi LAT Collaboration and Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSFПредполагаемые traces the decay of particle dark matter in the Andromeda galaxyRussian scientists have understood how to create dark matter of neutrinos© Photo : NASA/DOE/Fermi LAT Collaboration and Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

Scientists from the Institute for nuclear research RAS formulated a new physical model that allows you to create the necessary research the amount of dark matter from neutrinos. The work was carried out within the framework of the project supported by the Russian science Foundation grant, and its results were published in journal of Cosmology and Astroparticle Physics (JCAP) and presented at the conference 6th International Conference on New Frontiers in Physics.Dark matter is 25% of the total matter of the Universe, emits no electromagnetic radiation and does not interact directly with it. The nature of the dark matter is for certain, nothing is known, except that she can be clustered to gather in thickening. To describe dark matter astrophysics extend the Standard model of particle physics is well-established in theoretical physics, a theory that describes the electromagnetic, weak and strong interactions. Today, scientists have come to the conclusion that this model does not fully describe the reality, because does not take into account neutrino oscillations – transformation of different types of neutrinos into each other.

Neutrinos are fundamental particles with no electrical charge (neutral). Neutrinos participate only in weak and gravitational interactions, because the intensity of their interaction with anything is very low. Neutrinos are «left» and «right». «Right» called sterile neutrinos, they, unlike others, is not contained in the Standard model and do not interact with the particles – carriers of the fundamental interactions of nature (gauge bosons). In this case sterile neutrinos mixed with active neutrinos, which are the «left» particles and are present in the Standard model. To active neutrinos such as neutrino, in addition to sterile.

© Roy Kaltschmidt, Lawrence Berkeley National LaboratoryДетектор neutrinos inside viewRussian scientists have understood how to create dark matter of neutrinos© Roy Kaltschmidt, Lawrence Berkeley National LaboratoryДетектор neutrinos inside view

Scientists conducted a study of the spectral lines of the x-ray range, not so long ago discovered in the radiation from a number of clusters of galaxies. This line corresponds to photons with an energy of 3.55 Kev. Usually this would mean that these atoms will emit these photons due to the transition of an electron from one level to another, however, substances with a difference transition between the levels of 3.55 Kev do not exist. Scientists have suggested that this x-line could appear because of the decay of a sterile neutrino into a photon and an active neutrino. So the authors determined that the mass of the sterile neutrinos was equal to about a 7.1 Kev. For comparison, the mass of a proton is 938 272 Kev.

© Photo : Institute of nuclear research Rostunova «Troitsk nu-mass»Russian scientists have understood how to create dark matter of neutrinos© Photo : Institute of nuclear research Rostunova «Troitsk nu-mass»

Sterile neutrinos can be detected in terrestrial laboratories such as the «Troitsk nu-mass» and KATRIN. These units aims to search for sterile neutrinos using radioactive decay of tritium («heavy» hydrogen isotope 3H). On the «Troitsk nu-mass», located in the city of Troitsk in Moscow region received the most severe restrictions on the square of the mixing angle. The mixing angle is a dimensionless quantity that characterizes the amplitude of neutrino transition from one state to another. Same measured value is the square of this angle, as it defines the probability of transition in a single act of interaction.

«In this paper we propose a model in which oscillations, i.e. the birth, the sterile neutrinos do not start in the early stages of evolution of the Universe, but much later. This leads to the fact that the sterile neutrinos is less, and, therefore, the mixing angle can be more. This is achieved through changes in the hidden sector. A hidden sector of the model consists of sterile neutrinos and the scalar field. A scalar field is responsible for a qualitative change (phase transition) the structure of the sector. The birth of sterile neutrinos is only possible after this phase transition. Therefore, in our model, sterile neutrinos are born smaller, which thus allows to produce the right amount of dark matter from a sterile neutrino with mass of order Kev with a large square of the mixing angle up to 10-3,» — said one of the authors of the article Anton Chudaikin, Intern researcher at Institute for nuclear research, Russian Academy of Sciences.

As scholars have noted, the possibility of producing the right amount of dark matter from neutrino of a certain mass of interest from the point of view of cosmology.

© National Astronomical Observatory of Japan and the Hyper Suprime-Cam ProjectСозвездие Cancer with the Subaru telescope. The contour lines indicate the distribution of dark matterRussian scientists have understood how to create dark matter of neutrinos© National Astronomical Observatory of Japan and the Hyper Suprime-Cam ProjectСозвездие Cancer with the Subaru telescope. The contour lines indicate the distribution of dark matter

The fact that earlier cold dark matter consisting of heavy and slow-moving particles, does not prevent the formation of dwarf galaxies, is well described by the entire set of experimental data. With the improvement of the experiment revealed that in fact, these galaxies are smaller than expected. This means that dark matter is most likely not all the cold, there is admixture of warm dark matter, which consists of more fast and light particles. It turns out that the theory and the research results are dispersed, and scientists had to explain why it happened. They concluded that dark matter contains a small fraction of light sterile neutrinos, which would explain the scarcity of dwarf satellite galaxies.

© Anton Codeinenoprescri on the parameter space «square of the mixing angle – mass sterile neutrinos» in the proposed model (color shows the fraction of sterile neutrinos to the total energy density of dark matter) and from direct searches (green line).Russian scientists have understood how to create dark matter of neutrinos© Anton Codeinenoprescri on the parameter space «square of the mixing angle – mass sterile neutrinos» in the proposed model (color shows the fraction of sterile neutrinos to the total energy density of dark matter) and from direct searches (green line).

Light sterile neutrinos, however, may not constitute all dark matter. Recent studies in this area say that the proportion of lightweight components in the total density of dark matter today should not exceed 35%.

«In the future a positive signal with any of these settings might be an argument in favor of the proposed model, which will lead to qualitatively new understanding of the nature of dark matter particles in the Universe», — concluded the scientist.

The work was done in collaboration with scientists from the Moscow physical-technical Institute and the University of Manchester (UK).

 

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