Observations of distant galaxies have helped astronomers find out that dark matter is distributed much more evenly across the cosmic web of the Universe than scientists had previously assumed, which indicates the need for a complete revision of cosmology, according to an article published in the journal MNRAS.
“We are now seeing a very strange but interesting discrepancy with the observations that we obtained with the Planck telescope in the recent past. Subsequent missions such as the Euclid probe and the LSST telescope will help us repeat these measurements and understand what the universe is really telling us,”said Konrad Kuijken of the Leiden Observatory in the Netherlands.
It is believed that the universe is similar in structure to a giant three-dimensional web. Its threads are clusters of dark matter, the so-called filaments. At the points of intersection of these filaments there are dense lumps of visible matter - individual galaxies and groups of stellar megacities. In July 2012, astrophysicists were able to detect one of these filaments connecting galaxies Abell 222 and Abell 223, thanks to distortions in the light of distant stars caused by dark matter.
Scientists study the structure of this web by observing thousands of distant galaxies using ground-based and orbiting telescopes, and fluctuations of the so-called relict radiation, the "echo" of the Big Bang, in which information about the distribution of dark matter in the Universe was imprinted.
The filaments of dark matter, as Kuiken explains, distort light in a special way when it passes through them, which makes it possible to calculate the thickness of individual elements in the "cosmic web" of the Universe by how much the lines are stretched in the spectra of galaxies distant and close to us.
Observing 15 million galaxies as part of the KiDS project with the VST telescope, European astronomers have found that the filaments of the "cosmic web" through which their light passes or in which they are located are unexpectedly thin, much less than theory predicts and observations show the Planck space telescope, which monitored fluctuations in the relict radiation.
This means that dark matter is distributed throughout the Universe much more evenly than we are used to thinking, and that a much larger fraction of the mass of the universe is contained in the voids between the threads of the "cosmic web". Or another, even more frightening option is possible - the distribution of dark matter in the early Universe, which was observed by "Planck", was completely different than today.
Such discrepancies, scientists say, indicate that our current ideas about the structure of the Universe, explaining the existence of the "web" and the nature of the distribution of dark matter in it, are incomplete and need to be revised. Astrophysicists hope that a new generation of ground-based and space telescopes will help find the reason for the discrepancy in the KiDS and Planck data.
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