2023-09-24 06:00:10
How much matter is there in the Universe? An international team of researchers succeeded in measuring this crucial quantity and thus validating a previous measurement. Their study reveals that matter, including dark matter, makes up 31% of all matter and theenergy of the’Universe. The rest is dark energy.
Dr. Mohamed Abdullah, researcher at the National Research Institute of Astronomy and Geophysics in Egypt and theChiba University in Japan, indicates that only 20% of this matter is called “baryonic”. This includes things like stars, galaxies, and atoms. The remaining 80% is composed of black mattera still mysterious substance.
To reach these conclusions, the team used a proven method. They compared the number and mass of observed galaxy clusters with predictions from numerical simulations. Gillian Wilson, Abdullah’s thesis advisor and professor of physique at UC Merced, explains that the number of these clusters is very sensitive to the quantity total matter in the Universe.
Anatoly Klypin of the University of Virginia adds that it is difficult to precisely measure the mass of a galaxy cluster. This is mainly because most of the matter in these clusters is dark matter, invisible to telescopes. The team therefore had to use an indirect indicator: the number of galaxies in each cluster. The more massive a cluster, the more galaxies it contains.
The researchers thus estimated the total mass of each cluster in their sample from the Sloan Digital Sky Survey. THE data were consistent with a Universe composed of 31% matter. Tomoaki Ishiyama,Université of Chiba, specifies that these results agree perfectly with the observations previous ones carried out with the satellite Planck.
The study also demonstrates the power of spectroscopy to determine the distance of each cluster and identify the galaxies gravitationally bound to it. This level of precision was unattainable with the more rudimentary imaging techniques used in previous studies.
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