The gamma-ray background is not detected traces of dark matter
Within the last ultra-precise analysis of cosmic gamma-ray background, scientists have not found in him no trace of dark matter. Under gamma background meant unexplained traces of gamma radiation, from time to time observed in all corners of the universe. Initially it was believed that gamma rays can be somehow connected with the equally mysterious dark matter, but recent research suggests that the puzzle much more difficult than it might seem at first glance.
Sami gamma rays consist of photons that are visible to the naked eye, but these photons have the highest energy content of all photons of types known in the universe. They have such a high charge that can ionize matter, for example, to change our cells. Note the presence of scattered gamma-ray background, scientists began back in the 1960s.
To date, it has been found about 3000 extragalactic sources of gamma-ray background, but the number of detected sources are not correlated with the amount of this most of the observed gamma-ray background. In fact, it turns out that more than 75 percent of gamma rays in the universe are unknown sources for us.
As far as is known, then one of them could conceivably be blazars - one of the most energetically powerful events in the Universe, is a compact quasar associated with the hypothetical supermassive black hole located in the galactic center and releasing a tremendous amount of electromagnetic radiation. Other sources are pulsars and supernovae. However, all these sources can not explain such a volume of background gamma radiation. But from somewhere in the background should still be taken? Scientists say that "if we had a gamma-sight and looked up at the sky, you would not find there any dark places - so dense is the background." Interest in it in the first place is the fact that, according to the researchers, the gamma-ray background can contain prints of dark matter particles, which, in turn, could be the answer to the other, no less important question - why the number of visible matter does not relate to the volume of gravity, which is available in the universe?
That hypothetical dark matter - a kind of matter, which is invisible due to the fact that it does not interact with electromagnetic radiation - could explain why the universe has so much extra gravity. The trouble again is that this dark matter nobody has seen. But it is there, because its gravity it affects the galaxy.
Scientists believe that if dark matter can explain the amount of gravity in the universe, it is quite possible, it will be able to explain other strange things like the number of background gamma radiation.
To see if it would work, a group of scientists from the University of Amsterdam under the direction of Mattia Fornazy using powerful telescopes, including the NASA Space Fermi gamma-ray telescope, carried out scans of gamma background in search of vibrations that could bring researchers at their source. In total, the researchers analyzed data collected by the Fermi telescope for the 81-month period.
By studying these oscillations, the researchers found that gamma-background in general consists of two types of gamma radiation: what comes from the high-energy sources, and that goes from the low-energy sources.
Where is it?
Based on the analysis, scientists have found evidence suggesting that the source of high-energy gamma rays can not yet be detected blazars - the hypothesis of the existence of these facilities is currently being studied by several independent groups of researchers.
At the same time the source of low-energy radiation remains a mystery. However, the team noted that these sources can not be blazars, pulsars and supernovae. As the dark matter. At least so say the complex computer simulations. They show that the annihilation or other types of collapse of dark matter can not play any role in any creation of gamma-ray background.
"Our measurements complement the studies of other research groups who have tried to use gamma rays to search for dark matter. Results of the analysis show that in the isotropic gamma background does not contain traces of exposure to gamma rays of dark matter "- says Fornaza.
Research scientists Amsterdam was accepted for publication in the upcoming issue of Physical Review D. At the moment, all the information about the study is in the arXiv.org e-library.