According to the cosmological model, Lambda-Cold Dark Matter (ΛCDM), the universe is more than 95 percent filled with dark matter and dark energy. Ordinary (baryonic) matter is composed of protons and neutrons, accounts for only 4.6 percent. However, observations show that the stars, the interstellar medium and the hot gas in galaxy clusters (clusters) contains only 50 per cent of the theoretical amount of baryonic matter.
Matter in the Universe forms a three-dimensional network, the nodes of which formed under the influence of gravitational forces. These nodes, consisting of large galaxies or galaxy clusters and dark matter, bound filamentous structures. The results of the hydrodynamic modeling showed that between clusters must be missing part of ordinary matter. It is called warm-hot intergalactic medium (WHIM). However, it is difficult to detect because of the very low density.
The researchers analyzed data collected by the Planck orbital Observatory designed to study the cosmic microwave background (CMB or CMB) left after the universe became transparent to thermal radiation. The scientists looked for changes in the background caused by the passage of CMB photons through the warm-hot intergalactic medium, which would be located between the bright red galaxies (Luminous Red Galaxies). This phenomenon is called the Sunyaev-zel'dovich effect.
Just was studied 260 thousand galaxies. It turned out that the filamentary structures between baryonic matter several times denser than the average in the Universe.