2024-01-12 13:42:31
CMB radiation is the background thermal radiation of the Universe, which arose in the first stages of its development, during the era of primary recombination, when matter cooled sufficiently and the first atoms were formed. Astronomers first detected this light in the form of dim microwaves in 1965.
In the 1970s, it became clear that this radiation is not only uneven, but has a dipole structure: in one direction it is slightly hotter than in the opposite. This was measured more accurately later, using the COBE observatory, which operated from 1989 to 1993. It turned out that in the direction of the constellation Leo, the relict radiation is regarding 0.12% hotter and, on average, stronger. It is believed that the reason is the movement of our solar system relative to the background.
This difference interferes with the study of weaker differences in background radiation, so observational data is usually stripped of it. The problem is that microwave radiation is not the only background radiation in the Universe, but so far only it has been measured with sufficient accuracy. And to test hypotheses regarding the cause of the dipole, you need to see the full picture.
Therefore, a group of scientists decided to select from observations of the LAT gamma-ray telescope of the Fermi space observatory over 13 years all data on gamma radiation with an energy above three gigaelectronvolts. For comparison, the energy of visible light is two to three electron volts.
The researchers then “cleaned” the data from radiation from the Milky Way’s disk and known sources of gamma rays. Then the scientists saw an unexpected change in intensity. Results of work published V The Astrophysical Journal Letters.
“This is a completely random discovery. We found a much stronger signal than the one we were looking for in a different part of the sky,” commented one of the authors of the study is Alexander Kashlinsky, a cosmologist from the University of Maryland (USA).
The source of gamma radiation turned out to be in the southern hemisphere, while the peak of the cosmic microwave background radiation is in the northern hemisphere. But it coincided with a source of ultra-high energy cosmic rays (UHECR), whose energy is billions of times higher than three gigaelectronvolts – the minimum value by which the authors of the new work sifted the Fermi data.
It is noteworthy that not only the direction coincided, but also the difference in intensity – 7% more gamma rays and particles “arrive” from this area of the sky than on average. And in the opposite direction there is a similar decline. Fluctuations in the amount of cosmic ultra-high energies were discovered not so long ago, in 2017. Scientists logically assumed that these phenomena are related to each other and have a common source. Maybe these are neutron stars or active galactic nuclei.
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