Gravitational lensing around an incredibly dense galactic cluster

Gravitational lensing around an incredibly dense galactic cluster

Dark matter halos are theoretical bodies within which galaxies are suspended (the halo mass dominates over the total mass). These halos cannot be observed directly, but scientists discover their presence by the phenomenon of gravitational lensing - distortion of background objects by strong gravitational sources acting as lenses. Researchers are even able to study distant galaxies, increasing by gravitational lensing from closer objects.

For decades, astronomers have known that the process of galaxy clusters does not reflect the accumulation of most of the matter of the Universe. The concept that the distribution of galaxies correlates with the density of matter in a particular spatial region appeared in 1984. In the galactic cluster, the distribution of matter is strongly grouped, and halos are formed at the peak of this distribution. This is referred to as halo offset.

Gravitational lensing around an incredibly dense galactic cluster

Visible light and total mass. This is a composite color image of the PSZ2 G099.86 + 58.45, using CFHTLS g, r, and i snapshots. The contours follow the mass distribution reconstructed from WL (white) and optical light (red) of galaxies with a photometric redshift of ± 0.06 (1 + zcl) times the cluster's displacement. The longer the dash, the higher the contour value Recently, Italian scientists have studied the PSZ2 GO99.86 + 58.45 - an extremely dense galactic cluster with a strong gravitational signal. They reported that the system is extremely rare within the framework of the formation of a galactic structure, and its characteristics hint at the effectiveness of enhancing mechanisms other than mass in the halo of dark matter.

The shift data shows that the edges of the cluster are endowed with an extremely large gravitational lens signal that can be traced up to 30 megaparsec. High signal-to-noise ratio implies medium density, which greatly exceeds the average cosmological density. And the bottom line is that this extreme density cannot be explained only by mass.

Their results are in excellent agreement with the Lambda model of cold dark matter, which claims that the Universe contains a cosmological constant (Λ) associated with dark energy and cold dark matter. The latter is a hypothetical form of dark matter, where particles move slower than light. This model assumes that the structure of the universe forms a hierarchical bottom-up structure.

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