An international group of astronomers led by Richard Massey from Durham University in England has denied the "lightening" of dark matter, that is, the existence of a non-gravitational interaction between clumps of invisible matter. The preprint of the scientific work is available in the arXiv.org repository, the article itself is accepted for publication in the Monthly Notices of the Royal Astronomical Society.
On April 15, 2015, the same journal published an article "The behavior of dark matter associated with 4 bright cluster galaxies located in the 10 kpc core of Abell 3827". In it, astronomers reported the discovery of signs of non-gravitational interaction in dark matter, which is located in the galaxy cluster Abell 3827, 1.3 billion light-years from Earth. The researchers studied the distribution of mass in four colliding galaxies using the effect of a gravitational lens, when an object bends the path of light rays.
It is assumed that there is a dark matter halo at the centers of galaxies, which explains the peculiarities of the circular motion of stars around the nucleus. Three clumps of dark matter in Abell 3827 corresponded to the location of three galaxies, but the fourth clump in its motion lagged behind a nearby galaxy by five thousand light years. This, according to scientists, indicated that not only gravitational forces act in dark matter, but also some other interactions.
In the new study, astronomers used the Atacama Large Millimeter Array and Very Large Telescope complexes of radio telescopes in Chile, which allowed for more detailed spectroscopy of galaxies and minimized distortions caused by the effect of gravitational lensing. It turned out that the location of the halos in galaxies corresponded to the ΛCDM model, according to which dark matter interacts only through gravitational forces.
Dark matter, according to cosmologists, makes up 22 percent of the entire mass of the Universe (74 percent is dark energy, and the rest is visible matter). It does not interact with ordinary matter through electromagnetic and other fields, with the exception of gravity. The conclusion about its existence was made on the basis of observation of astronomical objects, which behaved as if they were influenced by mass hidden from direct observation. At the moment, no particles have yet been discovered from which dark matter could exist.