An international team of researchers from the University of Berkeley and the Berkeley Lab has managed to decode the faint distortions in the pattern of the first light of the Universe and reveal the enormous, but invisible for the naked eye, tubular structures that function as authentic “superhighways” and which send huge amounts of matter to the densest points, such as galaxy clusters. In other words, these structures, authentic “rivers of light and matter” are the filaments that form the so-called “cosmic web”, the immense network that controls the distribution of matter on a large scale in the Space.
To achieve this, the scientists analyzed a large number of data from previous sky analyzes but using a new and sophisticated image recognition technology capable of identifying the gravitational effects that give shape to the filaments.
The study helps for better understanding of the cosmic webs formation
Just published in Nature Astronomy, the study will help to understand how the cosmic web was formed and evolved, the great structure that groups all the matter of the Universe, including the mysterious dark matter, five times more abundant than the ordinary matter that forms planets, stars, and galaxies.
In fact, apparently the filaments themselves are made of dark matter, and researchers have been able to see how these enormous cosmic strands stretch and bend over hundreds of millions of light years, converging in points of great density of matter, where large galaxy clusters are housed, which are continually “fed” by this incredible network.
The researchers believe that these studies may also shed light on the even more mysterious dark energy, the force that is believed to be responsible for the universe to expand more and more quickly.
“Normally, researchers do not study these filaments directly, but focus their observations on galaxies,” says Shirley Ho, one of the researchers.
In this way, the team of scientists managed to produce a whole catalog of cosmic webs, which connected the conglomerates of matter observed in other studies.
Scientists also measured the CMB (cosmic microwave background) of the cosmic webs
The researchers also carried out precise measurements of the cosmic microwave background, or CMB, which is the faint remaining and almost uniform radiation of the first light of the Universe. Although this radiation is practically the same throughout the Universe, there are slight fluctuations in it, already identified in previous works.
In their study, Ho and his colleagues focused precisely on those small fluctuations in background radiation. To do this, they used sophisticated algorithms to find the location of the filaments in the distortions caused by gravity in the CMB, known as “weak lens effects” and that originate when the CMB radiation passes through matter.
Since galaxies are located in the densest regions of the Universe, the weak signal of the lens effect that reveals the deflection of the CMB light is strongest in those areas. Dark matter resides in the haloes around these galaxies and it is known that from there it also extends in the form of filaments.
“We were not just trying to connect the dots but we were trying to find those crests in the density, the points of maximum local density,” the researchers pointed out.
Due to the “competition” between the attraction of gravity and the expansion of the Universe, both the filaments of the cosmic webs and their connections can vary and change in shape over time scales of hundreds of millions of years. The study, the only complete one so far, allowed the researchers to determine the length of the filaments, something that will serve to find clues about the properties and content of the immense “voids” which are huge regions of hundreds of millions of light years in which apparently there is no matter formed around the filaments.