How is matter distributed in the universe? Nearly 150 researchers have just given the most definitive answer to this question in a series of 3 papers published Tuesday, January 31, 2023, in the journal Physical Review D. This study is based on data provided by two instruments: the Dark Energy Survey telescope installed in Chile, and the South Pole Radio Telescope, which, as the name suggests, is located at the South Pole.
Describe how matter was distributed throughout the universe over the 13.8 billion years of its existence.
The first mapped over 226 million galaxies around us in six years of measurements. The second was devoted to the study of the cosmic microwave background (CMB). This is the very first image of the universe when it was only 380,000 years old. It is actually radiation with a temperature of about 3 Kelvin (-270°C). The tiny fluctuations around this 3K value indicate where matter will eventually cluster. Thus, the efficiency itself is the oldest map of the distribution of matter.
Thus, by combining the results of these two tools, one can describe how matter was distributed in the universe as it expanded over the 13.8 billion years of its existence.
A slight deviation from the models of the description of the Universe
For researchers, then the question was to compare this result with the models of the Universe at their disposal, which simulate the action of classical matter (5% of all matter and energy of the Universe), dark matter (27%) and dark energy (68%), responsible for accelerating the expansion of the Universe. . These three components do work to explain the current distribution of matter, “classical” as “black”.
By comparing the simulation result with this map, the researchers found little difference. “It looks like there is a little less fluctuation in the current universe than we expected,” Eric Baxter, a co-author of the analysis and an astrophysicist at the University of Hawaii, said on the University of Chicago website. In other words, the universe contains more “chunks” of matter (at least chunks the size of a cluster of galaxies) than expected.
This is bad ? Not yet, because if this map is more accurate than the previous ones, it has not yet reached a level of detail sufficient to claim that the models are wrong. On the other hand, if this discrepancy were confirmed by other studies, then this would mean that the models need to be modified, for example, by adding a “mysterious” ingredient …